Hi pedroca, first of all i want to welcome you here!
Of course you are right if you say that the first improvement of 220 points were easier than the increase to 700+. That does not only need hard work and commitment but also the ability to solve the hard questions. The test tries to trap you or play games with your brain. All questions can be solved within 10-15 minutes, BUT you only have round about 2 minutes in average.
1. Brush up your fundamentals (you are not able to manage 700+ with weak fundamentals knowledge)
2. Have a study plan (estimate how many hours you are capable to spend each day) and stick to it. Not on a daily basis but on a weekly.
3. Go through
MGMAT (8books) and solve the questions in the OG12 accordingly
4. Start with GMATPrep Test and analyse your weaknesses and strenghs (use an
error log). Do not rush through the review. Analyse each and every question (even though you answered it right) to learn more about concepts and tricks. You might be able to answer a question correct, but most of the times there are faster approaches more efficient
5. go back to your study books and brush up the fundamentals, which you got wrong at the CATs
6. Try the
gmatclub tests (really hard) - if you are at Q46-Q48 it will help you to improve. Same with verbal
7. Practice, Practice, Practice....
Good luck with your study.