If you saw only a few questions repeated, that's okay. You can still take both GMATPrep and MGMAT CATs with repeats as long as you follow a few guidelines to minimize the chance of artificially inflating your score via question repeats.
First, anytime you see a problem that you remember (and this means: I know the answer or I'm pretty sure I remember the answer, not just "hmm, this looks vaguely familiar..."), immediately look at the timer and make yourself sit there for the full length of time for that question type. This way, you don't artificially give yourself more time than you should have.
Second, think about whether you got this problem right the last time. If you did, get it right again this time. If you didn't, get it wrong again. If you *completely honestly* think that you would get it right this time around if it were a new question (even though you got it wrong last time) because you've studied that area and improved, then get it right this time.
Have you already done both of the free GMATPrep tests from mba.com? If not, download those. (Note: they don't give you very much data to analyze, unfortunately.) They also sell two additional practice tests for about USD40.
Next, you're looking to lift your score about 100 points in a month. That's ambitious; most people would need more time. I'm not telling you that you can't get 100 points in a month, but you should think about what you want to do if you realize that it's not going to happen. Would you rather postpone your test? Lower your goal score? A combination of the two?
Okay, for specific advice, I need you to tell me many things first.
First, read these two articles:
http://tinyurl.com/executivereasoninghttp://tinyurl.com/2ndlevelofgmatThink about how what you've been doing does and doesn't match up with that and how you may need to change your approach accordingly.
Then, use the below to analyze your most recent MPrep CATs (this should take you a minimum of 1 hour):
http://tinyurl.com/analyzeyourcatsBased on all of that, figure out your strengths and weaknesses as well as any ideas you have for what you think you should do. Then come back here and tell us; we'll tell you whether we agree and advise you further. (Note: do share an analysis with us, not just the raw data. Your analysis should include a discussion of your buckets - you'll understand what that means when you read the last article. Part of getting better is developing your ability to analyze your results - figure out what they mean and what you think you should do about them!)