As said, there are some things you can get out of such a problem. (Like saying "ah you got me!" then using an alternate sleight.) If you think the trick would not be critically impaired because of the insight your spectator got into the method you can just plow on ahead. However, if they really did just figure it out, I don't try to wiggle my pride out. I just say, "You caught the sleight, nice. Most people don't get that one. Well, do you want to see one of my easier tricks? (Sure, they say.) Ok," and then you whip out BeLieve or some other heart stopper (Control, maybe?).
I preface all my magic by saying, casually, that most people suddenly get on guard when they are shown magic, and all they want to do is figure out the trick. Their purpose in watching isn't to enjoy the trick; it's to figure it out so the magician doesn't get to have pride over them. I ask my audience just to lay back and enjoy; if they see a slight or mess up to feel free and tell me, but otherwise just enjoy what happens.
More or less, that's the jist of what I say. Sometimes I like to say it a time when I'm not about to do magic.