Would this be stupid?

So my GPA suffered a lot during sophomore year due to my courseload (decided to take AP World, AP Calculus AB and BC, and AP Chemistry… what a great idea) and I ended up getting a lot of B’s. Would it be reasonable to take a course like Calculus BC over the summer to try to get an A? Do you think that’s possible since I didn’t fail the class?

There is no reason to retake that class unless the grade would be used to completely replace the one currently on your transcript.