When you respond to your ex-husband's claims, you have the right to request that the Court order him to reimburse you for your reasonable counsel fees in connection with that action. After your ex-husband finds himself having to pick up the tab for your counsel fees once or twice, he will probably back off. You should discuss this with your attorney.
A stronger tactic, but one that should be used sparingly, is to file your own motion for sanctions. You can point out that his motions are merely intended to harass and cost you money and have no merit to them. I think if the judge is following the case and remembers his other rulings, this might succeed.
You should definitely consult with your attorney before making this motion.