Hi lsatlsat,
All you need is a 5-point improvement from your current score average, which is absolutely, positively doable in 4 weeks! If you're already getting scores in the mid-150's, that means you're leaving quite a few easy-to-medium difficulty questions on the table. Picking up those extra points alone will bring you to the 160's, assuming you can identify your weaknesses and fix them in the next four weeks.
I understand you've read the bibles and taken a course, so I would probably follow a self-study plan like the one below:
http://student.powerscore.com/self-stud ... y-Plan.pdf
While the plan is geared towards first-time test-takers, you can still follow it in its current format, as reviewing the foundational concepts for each section and question type is always a good idea regardless of where your strengths and weaknesses lie. After that, I would "tweak" the plan a bit to emphasize the areas most in need of improvement. Indeed, it is absolutely critical to identify the sections and/or question types that are costing you valuable points, and focus on these chapters from the Bibles and the coursebooks.
Let's say RC is my weakest section. I'd obtain the supplemental RC materials to the RC Bible, such as the RC Question Type Training and the RCB Workbook (
http://shop.powerscore.com/?action=prod ... 00O2WMsIAN). The Workbook provides excellent additional drills to practice with, while the Question Type Training volumes are invaluable as a way to apply the techniques you learn to actual RC passages. Alternatively, I might start downloading various RC collections from our Download store (
http://downloads.powerscore.com/question-collections/). Bottom line is, I wouldn't rely exclusively on practice tests: question collections, ideally grouped by type, are critical to developing an efficient study plan.
And, I would probably do some tutoring. Yes, it's expensive, but if you know what you want to get out of it, even a 5-hour package can make a tremendous difference in identifying your weaknesses and setting you in the right direction.
Keep in mind that the plan I'm referring to is a ton of work, requiring at least 20 hrs/week of test prep (QTT assignments, workbooks, practice tests, etc.). However, if you can pull this off by December, you will improve your chances of admittance tremendously. Don't postpone until February: there is no guarantee you'll do any better, but it's virtually certain that you will lower your chances by applying so late.
Hope this helps! Let me know.
Thanks!