I got in last year with about the same gpa as you, so don't worry too much about that. Definitely retake the ACT, or try the SAT I? Retake SAT II's as well, they aren't that useful till the 700+, remember you also need to take SAT II math. You definitely have a chance if you put everything you've got on the tests, as they can and will save you.
Don't know if this will help, but here are my stats when I applied last year.
uc gpa: 3.4~
sat 1: 600 cr, 780math, 720writing (you should go for higher in my opinion)
sat2: bio 720, math 780, lit 640.
These tests are really not that difficult, I recommend you to take a bunch of practice tests, that way you can get more familiar with them and develop your own test-taking strategies (such as scanning, etc). I know how stressful this experience must be, but you'll make it!
Make sure you get plenty of proofreaders for your essays. <------VERY IMPORTANT!