After my g/f orgasm, her clitoris becomes too sensitive, can be she build tolerance to continue?

If you need to continue after she has an orgasm, then it's about YOU and not HER. It makes no sense, and it is uncomfortable - can't understand why you'd need to do that. And why is it a PROBLEM, to anything other than the guy's ego? If it doesn't feel good, it doesn't feel good and your insistence on continuing to do such a thing is not really very intelligent. The time to prolong things is BEFORE orgasm. Or WAIT and then resume when SHE is ready.