I don't know if you applying to in-state schools, but I know that they are open to let you know when the admission committe meets to decide on which in-state applicant is accepted. Most state school select out of state candidates before (Oct & Nov.) state candidates (Dec & Jan)...unless you're an awesome applicant like 4.0 gpa and 25 DAT.
If your admission folks meet end of Jan. I don't see why you shouldn't take the DAT over and supplement your application before they decide on the complete class. I'm doing the same. I took my DAT in June and will be retaking at end of Dec. (before the admission committee meet). I already submitted my application and all my recommendation letters and stuff are in. I will supplement my application as soon as i get my scores in from my retake.
Here is the problem: the admission group may not call me for an interview if they think my gpa and dat scores from the first time is too low. Knowing this i still applied b/c when i apply next year, they will have the impression that i'm trying to get in their school and I've done things (retake DAT & more observation hours, etc...) to improve my chances of acceptance. If anything, it shows them that I'm interested in their school, I'm not going to give up, and I"m willing to work hard. Does that sound too sappy??? hahaha
Unless you have an excellent GPA, your chances of getting in this cycle will be difficult. But, like i said before, you can always supplement your application with a retake DAT, but only if your retake date is before the admission committee gathers to select the final list of students for the year. I think that means you have to take it before Jan. and you have to do well on the retake.
I hope that helps...I know your suffering...kekeke I"m there with you! Best of luck to you!