I agree with the above post. At the same time, I too have been trying to combat previous academic performance. The rule of thumb I have tried to follow is thus: Make A's. While a B+ or a B is not going to keep you out of medical school, you are playing the GPA game. The GPA points from having all A's is going to help raise your cumulative GPA (old and new work) by a greater degree than if you earn B's. And to be competitive, a 3.5 should be your target.
However, unless you took very few credits the first time around, the change is not necessarily going to be significant. After a year of class and solid 4.0 work, I was able to raise my overall GPA by 0.1...from a 3.38 to a 3.47. Granted, I was able to raise my sGPA by a greater margin. The more credit hours and GPA points on the transcript, the more and more classes you'll have to ace to increase your GPA by even a minuscule margin. (For instance, I have 200 credit hours and it would take me another 1.5 years at full-time to reach a 3.65, assuming I made straight A's.)
With this said, your recent coursework is okay. You've done well in some classes, but I, for one, would focus more on getting A's in your science courses. As I understand it, medical schools also look at your BCPM GPA, which consists of general chem, organic, bio, physics and math. You need to have that as high as possible (above 3.0 would be a good target).
So, in short, I don't think you're screwed. But that's just me... I sincerely believe that if you have the aptitude, want it bad enough and are willing to put in the work, you can make it happen! And, remember, grades are important, but they aren't the only thing the admissions committee looks at. You need a well-rounded application, including good MCAT scores (above 30), clinical exposure, volunteering experience, extra-extracurriculars, experiences displaying leadership, an outstanding personal statement, good letters of recommendation and interview skills.
I know that sounds like a lot (and it is), but take it one step at a time. Focus on doing well in your science classes. Lower your course load if necessary. Go slow and do quality work. You CAN make it happen!
P.S. I would highly recommend creating an Excel spreadsheet calculating your old GPA, current coursework and cumulative GPA - even breaking it down into the BCPM GPA. Doing so has been a huge help to me in ascertaining where I stand exactly and the grades I need to get where I want to go.