When the warranty expires, Apple will replace the battery for $99.00 + shipping. You send in yours and they send a replacement unit back with new batteries.. I don't know if it's new or if it's a refurb. See the link below:
Apple - Support - Battery Replacement Service - iPad
Do you charge every day? Every couple days? Does your iPad last a week?!
Also, what do you consider to be an optimal charging schedule to improve the non user serviceable battery?
This poll could be further expanded to include the "How long does your battery REALLY last" poll, and you can answer that question if you would like.