N2 JLPT in less than a month. What to focus on? Past tests?

I will be taking the JLPT this December 7 and I don't think I'm at the level where I can pass it yet.

Will spending 80% of my time on answering and reviewing past tests the best thing to do?

I think this would make myself familiarized with the test itself. However, I am worried that since it I'd only be studying past tests, they will not be doing past questions on the new test and I would be stuck trying to answer stuff that I did not actually study if that makes sense.

Are past tests enough considering I will study every vocabulary and grammar point I come across?

by Reisanta