Untitled

<html>
  <head>
    <script src="jquery-3.2.1.min.js"></script>
  </head>
  ...
  <form>
    {% csrf_token %}
    <input type="hidden" id="tk">
    ...
    <button type="button" id="download-button">Download</button>
  </form>
  <script>
    $('#download-button').click(function(){
      $("#tk").val($("[name='csrfmiddlewaretoken']").val());
      $("form").submit();
    });
    $(window).focus(function(){
      if($("#tk").val() == $("[name='csrfmiddlewaretoken']").val()){
        location.reload();
      }
    });
  </script>
</html>