Tired Jokes

So I've been rereading and revising UP NORTH for probably the seventh or eighth time and I've run into a problem. Stale jokes. One of the reasons the first draft flew by so quickly was because I was making myself chuckle every other paragraph. When I read it aloud to my wife, I did so with the delivery of a stand-up comic and smiled inwardly every time she giggled, snickered, and even scoffed or sighed. Now, after reading the same old jokes over and over again, none of it is funny. I can see how it could be funny. You know. To someone who hasn't read it before. But none of it is funny to me. It's like watching the same Seinfeld episode over and over and over again. I'm interested to see how other writers who do humor handle this problem. My guess is that I should probably stick it in a drawer somewhere for a while and read it again in three months. I'm just afraid I might never think it's funny again.