Welcome to the forum!
It's tough to increase by 200 points, but since you're still early in your prep I'd say you can still get a sizeable increase. Don't get too hung up on the magical 700...a GMAT score can't get you in and everyone seems to think that it's the magic number you need for your app.
How much practice did you do before the first test? How long has it been since you've studied quant or verbal stuff? It's important to understand GMAT strategy and brush up on math formulas, grammar rules, etc. and to do untimed practice questions before you start doing practice tests.
I would go through your PR book from beginning to end, one section at a time. Do the practice questions in the book as you go. After each section, do practice questions in the OG. Do maybe five of them and then check your answers. That way you can try to correct errors before you get into bad habits. Some people keep an
error log and find that helpful. People here seem to be pretty helpful too, if you can't figure out why the answer is what it is.
Be sure you also take the official GMATPrep tests. I personally thought GMATPrep and Princeton Review had the best tests. People here complain a LOT about how difficult and unrealistic Kaplan tests are, so I wouldn't take those, at least before you really know the GMAT. I think at least two or three people a day post something here or in other GMAT forums I visit, freaking out about their Kaplan scores. I have never seen anyone recommend Barron's for the GMAT...I would take that one back to the store.
2.5 months could be enough time to prep if you're able to study for a few hours every day. You might want to consider a prep class, though. The ones I checked out were about 2 months long, so look at that soon. Or you can work with a tutor or even do an online course. I suspect you'd get the most out of a class or tutor with the in-person instruction, though. But first do another week or two of serious prep, take another test, and then see how you're doing.
Hope this helps! Good luck conquering the beast that is the GMAT!!!