Super glue, razor blade, tweezers, isolation and patients. If you have just frags.
Basically relocate all your montis to a place a where you can inspect them every time you walk by the tank. At ANY sign of tissue stress/damage. Inspect the piece very carefully. Kill any nudis you can find w/razor blade/tweezers scrape off any eggs you can find (in a separate dish). Then super glue to fill in any crevices or areas your can't reach or see. If I have a frag on a plug, I will coat the entire underside of the monti and the plug with superglue to cover any eggs or nudis I may have missed.
If you already have them in your tank..inspect every piece even ones not showing signs of stress. Nudis have no issues eating the underside of montis for quite some time before you notice any damage ontop... ...by that time you have a full blown infestation instead of a few random nudis.
Dipping/ect just stresses out the coral in my experience.