Advice going from 152 to 160?

I got into a few schools this cycle but rejected from my top choice. My top choice school told me today that I should aim for a 160 to supplement my lower (3.3) GPA. I also have professional work experience.

However, any advice on going from 152 to 160 by June/July? what programs did you use? Or did you self study? Any advice helps!! Thanks :)