Hi ara.mbs,
I agree that two weeks is a pretty tight timeline, but in any case, here is some advice on how to improve your GMAT math score.
Regarding improving your math skills, my biggest piece of advice is to ensure you are studying in a topical way. In other words, be sure you are focusing on just ONE quant topic at a time and practicing just that topic until you achieve mastery. If you can study that way, I’m sure you will start seeing incremental improvement.
For example, let's say you are studying Number Properties. First, learn all you can about that topic, and then practice only Number Property questions. After each problem set, thoroughly analyze your incorrect questions. For example, if you got a remainder question wrong, ask yourself why. Did you make a careless mistake? Did you not properly apply the remainder formula? Was there a concept you did not understand in the question?
By carefully analyzing your mistakes, you will be able to fix your weaknesses efficiently and, in turn, improve your GRE quant skills. Number Properties is just one example; follow this process for all quant topics.
For some more tips on the best way to structure your studying, here is a great article:
The Best Way to Study for the GMAT