I would definitely not apply to a PTA program, simply because there are very few transitional PTA-DPT programs available and which would, in a sense, waste the time that you put into studying for your PTA (which, IMO, is very unfortunate and needs to be changed). The above suggestions were all good...I would also add looking into complementary programs as well, such as massage therapy (1 year, usually), ATC (usually a 2 year Masters), MPH, MBA, etc, depending on your particular practice area interests. Rather than retaking credits, graduate credits/degrees will be a great addition to your application and give you valuable skill sets that you will be able to use in your future career. You have a goal: this is an opportunity to make yourself a better therapist in the long run!