You do have to weigh the savings of renewal vs. new pass against the extra time though.
Let's say your pass expires at the end of June, but you won't be there until late July.
Renew now for $377.01 and your pass expires June 30, 2012.
Get a new pass when you go for $424.94 and your pass expires July 30, 2012.
So you get an extra month for $47.93. If you were planning on going that month, that could be great. If not, or if you get an AP year after yearr, it might not make any difference.