Low Undergrad GPA but 2 years Lab experience since graduating, How do I know where to apply?
I've been working as a research assistant at a fairly reputable lab for about 1.5 years


This is great, you've got actual experience working in a lab.


  By graduation I managed to raise my GPA to a 2.85


And this is going to be a major stumbling block for an admissions committee.

So far, you've done all the right things to get your academic career back on track.  The question is, what is the best strategy to overcome a 2.85 GPA.

Step 1: Make sure your GRE scores are stellar.  This would be a good idea anyway, but for you, this is likely essential.  With a bad GPA, your GRE scores will provide some evidence you've overcome your very bad academic start.

Step 2: Research more than one school.  Most schools have unpublished GPA cut-offs.  If your GPA is below that, a human likely won't even see your application.  There are ways around this.  One way is to have a professor at your current university contact professors at the university you'd like to attend and advocate for you.  Some schools may be able to special case your application if you have a professor already on your side.  Some schools won't budge on this.

Step 3: Make sure all of your letters of recommendation are from professors you've worked with and will be glowing.  Have them address how you've overcome your bad start.

Step 4: In your statement of purpose, address the low GPA and explain how you have committed to changes that have raised your GPA substantially from where it was.

Step 5: Bet on several schools.  Even people with great applications shouldn't assume they'll be accepted.  Apply to several schools, and ask your current professor to help you choose some that will overlook your GPA.  Talk with the person who runs your lab, and get their opinion of where your application would have the best chance of being accepted.  You may be best served by a smaller up-and-coming school or a school with a new-ish department.  

Finally: Make sure that every school you apply to is one you feel you'd be happy to attend.  Everyone applying to grad-school needs to do a gut check like this.  You're committing the next 4-7 years of your life to this school.