Update paper id field on reload

Change-Id: I538ad0b7b78fe97f0c27a2ab07908626a54c76f2
diff --git a/static/main.js b/static/main.js
index 277b4ef..6fd5249 100644
--- a/static/main.js
+++ b/static/main.js
@@ -3,6 +3,7 @@
     'use strict';
     window.addEventListener('load', function () {
         update_total_due();
+        update_paper_id_field();
         // Fetch all the forms we want to apply custom Bootstrap validation styles to
         var forms = document.getElementsByClassName('needs-validation');
         // Loop over them and prevent submission