Don't use CATs for practice. They serve other purposes:
- timing issues
- evaluating progress
- simulating test day conditions
- stamina

My advice is to practice using books such as the OG before taking another CAT. You'll see little improvement unless you target specific weak areas!

You'll find the free GMATprep software at mba.com. My advice is to go for CAT 1 two-three times and save GMATprep 2 for your final days before the test. That way you'll have an accurate prediction of your score.

Good luck!