There are some very upper tier med schools that are RUMORED to not invite for interviews unless you get an A in both ochem classes, these are just rumors though, no substance behind them. That being said, ochem is a REALLY important class, and if you retook it, do you think you would be able to pull off an A? You should retake it just because ochem 2 is a lot harder (many, MANY more mechanisms and reagents to learn) compared to ochem 1 and in your situation an A in ochem 2 is pretty much required, which in turn requires a really strong foundation from ochem 1. Don't worry about your GPA, you should be able to raise that, if not by application time at least by the 5th year if you end up having to stay longer than 4 years. Just worry about ochem! What part did you struggle with in particular?