I improved my CARS score by reading/listening to fiction. I know that seems oversimplified but it's great for memory and social cognition so you get better at picking up on syntax and tone in the passages. In a prep course I took, it was described as a total switch of gears compared to the rest of the test - which requires you accessing knowledge beyond the questions. CARS requires you to look only within the information given - do not rely on outside knowledge of passage topics to answer questions, which is where they can get you.
Also, I think that 9/3 would be a good date. My retake is on 9/4, but I'm retaking for C/P.