If you did well in your courses don't bother to re-take them. Take upper level classes and finish your pre-reqs at the university. No one will really care that you did some classes at Community College, unless you did badly for some reason. If that's the case, do re-take them, do well this time, and plan to answer the question of why you didn't do well at the Community College level when it comes time to interview. Best of luck!