I might retake the C+'s but not the B's. Also, do you really need the boost in GPA? If you're at that 3.5 range (which it looks like you are) and you have time to do better in your future courses then I would just focus and make sure to knock the rest of your classes out of the park. Don't worry too much about a bad grade or two early on in school. Just don't make a habbit of getting them.