I plan to retake the GRE, but I already got an AWA score I'm happy with. Can I just skip the AWA next time?

This is an interesting issue to talk about! After reading here, you might also want to check out this blog post on whether you should skip the AWA. That will give you Chris' take on the issue.

Whether or not you can skip the AWA on a retake of the GRE depends entirely on how the schools you wish to attend deal with GRE scores. You should never skip a section of the test before you know with 100% certainty how the admissions committee(s) are going to view your scores. In broad strokes, there are three main ways that universities handle the AWA:

1. The AWA is completely ignored/not used for assessing a candidate.
2. The AWA is used as a benchmark score (e.g. you need to get a 3 or higher, but simply passing this cutoff is all that counts).
3. The AWA is actually used as a vital component of assessing your readiness as a candidate.

In short, the AWA is not always a determining factor of a student's admissibility. While it can be an important part of your score, a lot of people tend to focus on just quant and verbal as their "main" score. Do not assume that you can mix and match scores from multiple tests. While it may be possible, it is not typical. 

To summarize, be very aware of what the admissions committees will want. If you do not know, assume that each test session counts in its entirety, and do your best on every section.