I assume the ex has filed the papers.
This would depend upon your local rules of civil procedure. If your local courthouse has a law library the librarian could help you find the rules on failure to prosecute.
However, normally, if you do not follow thru on pleadings you have filed, the other side can ask the court to throw the matter out. The caveat is that judges can be remarkably lenient with pro se litigants, especially if they feel that the pro se is at an intellectual disadvantage.
My advice – go ahead and file the papers. The worst the judge can say is no. However, you can probably ask the judge at the same time to order the ex to file the requisite papers under threat of dismissal.