Leroy,
I left a few years ago and like you I didn't receive anything from the AACA asking me if I'd like to continue my membership.
As mentioned above, it's easy to renew your membership either online or by contacting the Association Secretary at Wallop.
I visited the AACA tent at the IAS last year and had a great time, well worth your tenner a year to meet old mates and see the massed crash.
It would be nice if local branches were more active, but it seems some members are a tad apathetic when it comes to attending meetings and social functions. Nice to see the journal every year though.
Regards,
X-Quork