Is it time to replace your Mirage™ FX / Mirage™ FX for Her nasal CPAP mask cushions? CPAP mask cushions break down over the course of time from facial oils and begin to lose their effectiveness with a good seal. It is recommended to replace your CPAP mask or CPAP mask cushions every 3-6 months or when they begin to show the signs of wear and tear from nightly use