The change has to start with you. Whether you take a different course or study on your own, you will have to work to improve and find a way to look at the material differently.
Now I'm not as adamant as some of the other posters here against taking a different course for your second sitting, if you think you should take a course. Do what you feel/think you should do. You know yourself better than anyone. I would say that some people should study completely on their own (using different materials) for their second review. But, others benefit from a class. There are definitely some people who get a great deal from a class with a different (better) perspective on the material.
Ultimately, it will depend on where you are located. If you are in a region where all of the courses are essentially the same thing, then it would be a waste of money (and perhaps even more so time) to take a new class. But if you have an alternative to the corporate approach, then sit in on one of their classes and see if they do things in a way you like. If they do, then that might be your place.
Best of luck with round two and keep in mind that several thousand people take the MCAT twice and many of them improve. Change your atttitude and perspective, learn from your mistakes the first time, and keep the pedal to the medal for three months!