3 months is a lot of time. You should read the WSJ, NYT, Economist
and similar publications frequently to improve RC, for SC, use the MGMAT book
. For CR, use OG, MGMAT, just to keep on practicing. Find out what your weaknesses are in verbal and then concentrate on those. Keep a practice log, there're posts that talk about this. Go back to your old practice questions and find out whether you've understand what you did wrong in the past and whether you really mastered the concepts.
Best of luck!