I only took the PCAT once, but I did very well (99) on the quantitative section. To prepare, I'd advise you to just keep drilling the practice questions in the Kaplan book (or any other sources you have, but I just used Kaplan). Do the same questions over and over until you can do all of them quickly. Don't just memorize the solutions, but spend some time figuring out the very best way to solve each question as quickly as possible, then pay attention to the shortcuts you've started using.
Try to group the questions together by theme, like all the fraction/decimal questions, all the calculus questions, etc., and teach yourself which particular shortcut is applicable to which type of questions. This way you'll be able to use what you've learned on the new questions on test day. As just one small example, there are a fair amount of fraction/decimal type questions, so make sure you're proficient with cancelling out and simplifying numbers in the numerator and denominator of fractions you're manipulating...like 12/7 x 21/36 = 1/7 x 21/3 = 1 x 1
Hope this helps and good luck with your second attempt!
