I agree that you should retake the GRE. From what I read, GRE is generally used for two things:
1. If you have no or little experience, then you can use the GRE to make up for it. If you can score a 170Q on the exam, it tells the university that you have enough raw skills to make up for the inexperience.
2. It's used as a cut-off. If you have decent experience, but if you score poorly on the GRE Q, it might break your overall application.
Get a book and study the problems. Try to aim for 86%+. If you are aiming for the top 5, you probably need 92%+, but in general 86% in top 10-20 would be enough to make you a strong candidate. (For Verbal, try to get higher than 50%, you don't need anything ridiculously high)
Look at UCLA's average domestic stat: (http://www.cs.ucla.edu/academics/graduate-program/graduate-admission-frequently-asked-questions)
Domestic M.S. applicants/admittees: V: 73.3/78.2th; Q: 84.9/87.8th; AW: 57.9/62.2th.
Most importantly though, remember that the quality of SOP/experience/publications/recommendations will be a stronger indicator. Raise or lower your application range depending on it.