You will be able to use the retake when applying. Some PT schools will take the best grade. Some will average the two. HOWEVER, you likely will NOT get academic credit for it from your university if you've received a passing grade for it already. So, essentially, you'll be paying for a class that doesn't count toward your 120 credit hour requirement to graduate.
Also, I had 6 Ws and, in my interview, I was just generally asked to explain why my academic performance was lackluster in the beginning of college. However, I did have a pretty good last 60 hours GPA to show my academic and personal develpment.