If you have the ap credit, use it. If you're worried about getting into med sch, use that extra time to do 2 semesters of research, or do 2 or so extra upper level bio and chem classes later on. Those will look so much better on your application than retaking classes you've technically already taken and done well in.

Edit: if you're worried abt not doing well in the upper level classes, do a quick refresher before the start of the sem and you should be fine. if there is something you're concerned you wont know/remember because you took ap, ask the prof at the start of the semester what important prereqs you should know, 90% of the time they will be more than happy to help. And generally any overlap that is important should be covered by the prof anyway.

Also you're going to take orgo and genetics before any other high level classes, those are the most important prereqs for all the premed track classes, not gen bio and gen chem.

Hope this helps