If you haven't worked through the Powerscore bibles yet, I would say that you could improve your score a lot be Dec, you would just have to get started working through those and practcing as much as possible now. I would def. retake the test and then think about your options. With your grades, a good LSAT score can really help you get into a good school.
Also, if you score considerablly better, you might be able to get away with a school only considerng your new score if you write a good addendum to your application that explains why your score was low (provided its a good reason).
Also, one last item, this link from LSAC can give you a rough idea of your chances of being accpeted to a school based on LSAT and GPA. Please note that I said ROUGH idea:http://officialguide.lsac.org/UGPASearch/Search3.aspx?SidString=