570 to 600 after Veritas Prep ! Did you get stuck with a problem that took too much time? Any postmortem assessments?
GMAT exam from what I have gone through is obviously what I call intelligent practicing.
What you'll need to do is start analyzing how you do in the practice exams. At least one per week and then on the exam week at least two exams to get you into swing of things.
IF it takes you 3 hours to complete the exams you'll need to spend additional 3 hours just understanding your % hits, identify your weakness and then build proficiency in you weak areas and then check out if there was any improvement.
Furthermore, I have heard good thing about Veritas Literature and teaching. I am sure you have access to the recordings. Identify the classes, which focus on your weakness and review the recordings again. Don't read solutions to the problem. Take a crack at it first and then give it a shot.
Good Luck
Rohit