First things first: if you don't yet have the score that you want on practice tests, and you're not sure why, you should not take the test in one week. You may lose the whole test fee (you can only reschedule if you do so at least 7 days in advance), but that's better than taking it a 5th time without knowing what you're doing wrong.
Note: if someone is on only their first or second try and is already past the point of being able to reschedule, then I'd probably recommend that that person still take it. BUT the GMAT has a restriction: you're only allowed to take the test 5 times in any 12-month period. So if this is #5 for you, don't take it unless / until you are sure you're ready.
It is going to take us time to diagnose what's going wrong and why so that we can then put a plan in place to make things better (hopefully!). There's no way that this can all happen in 7 days. This may mean that you need to postpone your applications, too - if you really want to go to a specific school for which you need a higher score, then that's a decision you may have to make.
Okay, here are the steps for us to figure out what's going on. First, it sounds like your practice test scores and real test scores are in the same range (in other words, you're not experiencing a big score drop only on the real test). Is that right? Please tell us your test score history.
Next, we need to talk about your general approach to studying for and taking this test. 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. Take some notes as you go and when you're done so that you remember your thoughts / analysis.
Then, use the below to analyze your most recent MPrep CATs (this should take you a minimum of 1 hour):
http://tinyurl.com/analyzeyourcatsTake detailed notes as you go along.
Based 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!)