Wow, a 700 is still an awesome score!

I am currently in the same boat as you. I am not applying until fall, but I've decided to retest in mid-May before the format changes. I also scored a 6 on my AWA, and I figured, since I did well on that section, why risk the unfamiliar and possibly a lower score? However, the 6 you received on the AWA also strongly suggests that you're excellent at writing, so the new section may not phase you one bit.
You have until June 5th to study and retest. If your schedule does not allow you sufficient time to get studying done to fully prepare, then I would suggest waiting until the new test comes around. Otherwise, I would go with what you know!

Just my two cents...