Maybe find out whate exactly is tested on the 6th grade math test she took and didn't do as well as you had hoped. Maybe she missed a few dumb things or a few concepts that you can teach her at home.
Our teacher sent everyone last year a little packet to do at home right before the STAR tests, which is our state test. I realized my then second grader, for some reason, thought that 2:30 on the clock was 1:30. So I got the clock out and went over that with him,a nd he aced the real STAR test.