When I was preparing for CAT 2017, I faced a similar issue. I always scored between 100-120 (raw) and after a point was unable to push the score up. So, in this post, I'll share what I did, taking an example of the Quantitative Aptitude section. One month before the CAT exam, I was scoring 150-180 marks.
Score or Percentile?
First things first, let me share that marks are not a reliable measure to track to evaluate your performance in the CAT exam. I used two mock test series during my preparation - AIMCAT and Career Launcher. I often scored 120 marks in an AIMCAT and 150 marks in a CL mock and landed a 99 percentile in each case.
The percentile depends on difficulty level of the mock. So. if you're tracking mock scores alone, they might not show you the real picture.