Hi!
I think you should definitely take the retake within a month (and of course if you can see improvement in your performance) and not wait for September.
Since you mentioned Quants is your weaker section, I think it would be necessary to practice more. Of course, you can review some content you find particularly challenging, but I feel one can get comfortable with Quants only after actually solving a lot of problems. While practising you can make sets of 31 Qs to be solved in 62 minutes. Doing this often will get you ready for the test day.
If you are looking at signing up for any course, you must definitely consider TTP. They are simply the best for Quants. It might be challenging to finish the entire TTP course within a month because it is quite a comprehensive course and aims at making every concept crystal clear, but you can definitely try it for the weaker topics and solve all the chapter tests.
Hope this helps.