Do you swap it out with the next gun you're adequate with?
Do you not carry it until and X amount of rounds are run through it to ensure it's good to go?
Both of these, though I've yet to experience it. That's just what I plan to do if it ever happens. My Kimber UCDP has had no failures since the beginning 8 or 9 years ago. If it ever does, hopefully it'll be at the range, at which time I'll find out what's wrong and run at least another 100 rounds of Hydra-shoks through before I'll pronounce it GTG. In the meantime, I'll probably carry my Glock 26. I have several handguns that have never failed.
If it fails at the wrong time, I have to rely on my BUG, that is if I have time and option to deploy it.