What is the next math class that you would take? Are you eligible to take that class after a C+ in pre-cal? What is your college major likely to be? Will you even need math past pre-calculus? Why do you think you got that C+ grade in the first place? What exactly do you intend to do differently if you are allowed to repeat?
Personally, I’d advise you to spend some time reviewing the pre-cal materials with tutorials online at Khan Academy and PatrickJMT and see how well you start to handle the varios topics before you commit to your next math class.