Should I retake Chem II?

I got a 740 last June in Chem, and I am considering retaking it in May. I cannot retake in June cuz i have to take physics/math 2. I am looking at top schools; is a 740 going to be detrimental for schools like MIT. If i were to retake, I would have to relearn most of chemistry as I took it last year. Is it a waste of time to restudy considering I could study for APs instead?

I wouldn’t. If your planning on taking 2 other subject tests anyway, you may do even better than the 740 (which itself is a fine score). There are better things on which to spend your time.