Just say stuff like
"Cool! But you know what? YOU can't rise an INCH!
I'm sorry but that is most certianly NOT a good method of handling a spectator.
Another alternative to what I said in my post above is to say, "Wow, did you see what this David Blaine guy did? He levitated, like, a foot off the ground!You know I've been reading into his book and it teaches you about your inner energy and stuff. Look, I've been reading it for a week and now I can do this."
Then you use some invisible elastic loops and make something that is small and light move a bit on the table. With the right presentation it can look really good (don't forget that pushing objects with the mind is hard to make an effort out or it). Then, you can try and make it balance in an impossible way, and finally, if you're bold enough, make it float entirely a few inches off the table, and only for a few seconds.
Finally, look exhausted about the whole thing and take a lie down for a while (actually you just go off to your room and read a bit of AoA or something).
What you have done is implied that you don't expect yourself to be as good as David Blaine, but at least you're something. People hould respect that, provided they don't discover the secret and realise you're a phoney.
And leave it there. Don't even try the Balducci. The thing is about mind magic, especially PK and levitation is that to sell the illusion, the audience must believe that the magician had practised for several years (most likely involving travelling to some eastern country where he was taught about the art). If a young child performs the trick, that idea is out of the window. That leaves the idea that you are cheating. If people think you cheat then you're done for.