Don't skip it, but don't worry either...you will see what I mean.
Certainly you need to attempt the AWA, throughMBA has given the reasons for not leaving a blank...
You have gotten a 5.5 before so you know the drill. You know that you can do it. Now this time, relax and just let the AWA happen. You need to make sure that you do not "give it your all on the AWA" only to lose steam in the Quant and Verbal.
Last time I took the exam I made it a point to take it easy on the AWA. I wrote about the things that came to mind and did not worry that I might have left some fantastic example out there. I finished each one with 5 minutes to spare and got a 6.0.
Do the AWA, but treat it as batting practice. It can actually help your other scores if you use the AWA as a warm up. Get into the test, figure out if you need the earplugs or not, get yourself situated and very calmly just type out a nice essay.
So my advice to you, with the 5.5 already is that you can do a nice job without taxing yourself. You can actually make the AWA fun if you take the pressure off. Just remember that the schools get a copy of your essay so keep it professional and just let it flow. It will be over in no time and will be the most enjoyable part of the test - it is the only part where anyone wants your opinion!
Enjoy!