Hi, I believe you have to take all of the prerequisites within 5 years of applying to AA programs. If you need to retake them, then it could be your chance to improve your GPA. Some schools allow you to take prereqs at community colleges. From my experience, Emory and South seem the most selective. I would apply to all of the AA programs to improve your odds of getting in. You can apply to all of them through CASAA.

Just out of curiosity, may I ask why you are interested in becoming an AA? I was interested in becoming a cytotechnologist for a little while in college but never got around to shadowing anyone.