Hi DisciplinedPrep,
Early last week, GMAC made a formal announcement defining some changes that will be taking place to the format of the Official GMAT (beginning April 16, 2018). These changes primarily impact the overall length of the Exam (meaning the number of questions in the Quant and Verbal sections as well as the amount of time that you’ll have to complete each of those two sections). In theory, a shorter Exam could make it easier for a well-prepared Test Taker to score higher. Unfortunately, practice CATs in the new 'format' don't exist yet - but once they become available, you should plan to take one (so that we can get a better sense of how you perform under these new conditions). As an aside, it is UNLIKELY that the 'new format' CATs that you'll have access to will include 'new' questions (the various CAT providers will likely just reformat their existing CATs but still use the same pool of questions that are currently being used). This is meant to say that you'll need a new 'brand' of CAT that you have not used yet. Considering all of the CATs that you HAVE already used, your options will be limited. The CATs from Princeton Review would probably be the next logical choice.
Beyond those details, it's important to remember that taking lots of CATs will NOT make you a better Test Taker. A CAT is really a 'measuring device' - when used correctly, it will give you a realistic score and help define your strengths and weaknesses, but it will NOT help you to fix any of those weaknesses. To raise your scores, you have to put in the necessary practice and repetitions. The CAT will show you whether your studies are helping you to improve or not. The missing points that you're looking for are in the Verbal section, so your emphasis has to be on defining WHY you get Verbal questions wrong and what you can do differently to increase your chances of picking up those points.
GMAT assassins aren't born, they're made,
Rich