Don't let the cushion of a second and third attempt keep you from trying your best the first time.
Set a course for yourself and stick to it. Just like a good workout plan, you'll make no progress if you are constantly off and on for 3 months... you'd be much better off going virtually non-stop for 3 weeks.
Remember that the DAT is your chance to prove (or disprove...) your GPA. Your GPA takes years to accumulate but the DAT can alter your chances of acceptance dramatically in just 4 hours in front of that computer. Take the study process as seriously as that. This isn't just another test, it is THE test, so treat it that way!