Hi Farukqmul,
You are right - you definitely need to keep practicing quant. lest your skills get rusty

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Another important point is dividing up your study time between verbal and quant. While there is no magic ratio - each person has his/her own score goals, as well as his/her areas that need more focus - allocating at least 30% of your time to not only maintaining but improving quant, will allow you enough time to still focus on Verbal. In your case, you want to improve on quant by quite a few points so this ratio may come closer to 40% Quant/60% Verbal.
That said, make sure to work on areas in quant in which you are weakest. The key is to make sure you are performing at a consistent level across the variety of concepts (don't become a master of permutations at the expense of coordinate geometry). To identify these weaknesses - if you haven't already - take a mock test at least once every two weeks.
Once you feel confident in a variety of areas, don't content yourself with not being rusty. Definitely challenge yourself with some of the 700-level questions. Answering those questions test day will help you hit your goal of 45 on Q.
Good luck, and let me know if you have any other questions

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