Hi afdebbas,
It sounds like this is your first practice CAT. If that's the case, then we don't have much information to work with (regarding how you should best spend your next 3 weeks). You should plan to take a FULL-LENGTH CAT (including the Essay and IR sections) every week until your Exam.
With these Scaled Scores, you have an opportunity to pick up those 'missing' points in either the Quant or Verbal sections. Have you had a chance to review this CAT in detail? When doing so, you should make note of all of the questions that you COULD have gotten correct, but didn't because of a silly/little mistake. Adjusting how you do your work, so that you can keep those little mistakes form happening, should be your first priority.
GMAT assassins aren't born, they're made,
Rich