Page 2 Resets POST filter

i have following page where i filter posts based on their category. This filter works fine, but if there are multiple pages of filtered results and i click to go to page 2 the filter resets and shows every post again instead of page 2 of the filtered results. How can i go to the second page of the filtered results?

Code:

  <form class="form-inline" method="POST" action="/intranet/bibliotheek/">
        <?php $intranetCategorie = get_terms( 'intranet_categorie'); 
          if (!empty($intranetCategorie) && !is_wp_error($intranetCategorie )) {
           echo '<select class="form-control training-drop" name="intranetCategorie">';
           echo '<option value="empty">Alle Items</option>';
           foreach ($intranetCategorie as $terms) {
             if(0 != $terms->parent ){
                 echo '<option value="'. $terms->slug .'">' .$terms->name.'</option>';
               }
           }
           echo '</select>';
          }

        ?>

          <input class="btn btn-intra" type="submit" value="Filter Resultaten">
        </form>
          <?php foreach ($intranetCategorie as $terms) {
             $categorie[] = $terms->slug;
           } 


          if(isset($_POST['intranetCategorie']) && $_POST['intranetCategorie'] != 'empty'): 
              $categorie = $_POST['intranetCategorie']; 

          endif;
           ?>

          <?php 
            $paged = (get_query_var('paged')) ? get_query_var('paged') : 1;
               $args = array( 
              'post_type' => 'intranet',
              'tax_query' => array(
                'relation' => 'AND',
                                array(
                                  'taxonomy' => 'intranet_categorie',
                                  'field'    => 'slug',
                                  'terms'    => 'bibliotheek',
                                ),
                                array(
                                  'taxonomy' => 'intranet_categorie',
                                  'field'    => 'slug',
                                  'terms'    => $categorie,
                                ),
                              ),
              'posts_per_page' => 5,
              'paged' => $paged
              );

            $the_query = new WP_Query( $args ); ?>

            <?php if ( $the_query->have_posts() ) : ?>

              <?php while ( $the_query->have_posts() ) : $the_query->the_post(); ?>

                    <h3 class="intranet-title"><?php the_title(); ?></h3>
                    <p class="post-info">Geplaatst op <?php the_time('j F Y'); ?></p>

                      <p><?php the_content(); ?></p>

                    <?php 

                      $file = get_field('upload');
                      if (!empty($file)) {

                          if( $file ): 

                            // vars
                            $url = $file['url'];
                            $title = $file['title'];
                            $caption = $file['caption'];

                            // icon
                            $icon = $file['icon'];

                            if( $file['type'] == 'image' ) {

                              $icon =  $file['sizes']['thumbnail'];

                            }

                            if( $caption ): ?>

                              <div class="wp-caption">

                            <?php endif; ?>

                            <a href="<?php echo $url; ?>" title="<?php echo $title; ?>" target="_blank">

                              <img src="<?php echo $icon; ?>" />
                              <span><?php echo $title; ?></span>

                            </a>

                            <?php if( $caption ): ?>

                                <p class="wp-caption-text"><?php echo $caption; ?></p>

                              </div>

                            <?php endif; ?>

                          <?php endif; ?>
                          <?php } ?>

                  <?php if ( 'post' == get_post_type() ) : ?>

                      <footer class="edit">
                        <?php edit_post_link( __( 'Bewerk', 'soml' ), '<span class="glyphicon glyphicon-pencil"> ', '</span>' ); ?>
                      </footer><!-- .entry-footer -->

                    <?php else : ?>

                      <?php edit_post_link( __( 'Bewerk', 'soml' ), '<footer class="entry-footer"><span class="glyphicon glyphicon-pencil"> ', '</span></footer><!-- .entry-footer -->' ); ?>

                    <?php endif; ?>

                <hr>

              <?php endwhile; ?>
              <div class="pagination-links-intranet">
             <?php
            $big = 999999999;
            echo paginate_links( array(
              'base'        => str_replace( $big, '%#%', esc_url( get_pagenum_link( $big ) ) ),
              'format'      => '?paged=%#%',
              'current'     => max( 1, get_query_var('paged') ),
              'total'       => $the_query->max_num_pages,
              'prev_text'   => '« Vorige',
              'next_text'   => 'Volgende »'
            ) );
            ?>
               </div>

            <?php else : ?>
              <?php echo'<p>Er zijn geen berichten gevonden</p>' ?>
            <?php endif; ?>

Pagination after i filter on a category (working as intended):

Pagination after i select page 2 of the filtered results:

The filter resets and will show all posts again. It should go to the second page of the filtered results.