A couple of things come to mind.
1) Don't retake any science classes *unless* they schools
you're applying to really care about your science grades. Ask them. If they don't care, take transferable MSN classes instead.
2) How is your GPA for your last 60 hours? Many schools will consider your GPA for your last 60 hours if your overall isn't up to snuff.
3) Remember that GPA is only part of the acceptance picture. The six pieces to the puzzle are GPA, GRE, ICU experience, recommendations, interview and (the most important) your competition. If you have a lot of hardcore ICU experience this may trump your GPA. A killer GRE score will help. Great recommendations will help. You might assume that all of your competition has a 4.0, 20 years of cardcore ICU experience, a perfect GRE score and fifty-page recommendations from Dr. Swann, Dr. Ganz and Sir Issac Levophed - but they don't.