Hi,
So you know, a score can dip from one exam to another even with the same amount of knowledge or the same percentage of correct/incorrect. The GMAT scoring algorithm takes many factors into account, including where you make errors, how many mistakes you commit in a row, whether you finish both sections or leave questions out, whether the last few questions of either section seemed like they were guessed at, etc. I will refer you to the following articles on scoring:
https://econgm.at/Bd56c6https://econgm.at/hEut0lYou most likely still have practice material to cover. If you have some time, do keep on practicing as much as possible and take some practice tests throughout, intensifying as you get closer to the real test. Try to get as much official practice material as you can such as the Official Verbal and Official Quant Review, or the question pack 1, previous editions of the Official Guide for GMAT Review (12th and 13th editions are best), all from mba.com.
Whatever you do, do not ditch a few topics just to focus on the others... this will cause you to drop in those areas. Rather you should focus on your problem area and keep reviewing the basics of the areas you are already mastered on.
Sincerely,
Evan