If you're willing do do D.O. it's really up to you. Since D.O.'s allow grade replacement, you could retake all of those classes and do better. This would be better if you did not have a very good science foundation, because for M.D. it would be wise to just take more upper level science courses to raise your GPA and prove competency, but that would take a lot longer and is more risky in my opinion.
If I were in your shoes, I'd just retake them. That would help you get the material solid for the MCAT as well.