Since the launch of the iPad 2 I have been using a cover that I painted so I am reluctant to replace it. However the inside surface of the cover seems to be thinning or just becoming generally less fuzzy and it is doing less to clean the screen. In particular it is leaving vertical stripes that don't get cleaned. What kind of time are people getting out of their covers and is there any way to rejuvenate them or is there any material thin enough and effective at cleaning that can be bonded to the inside of the cover?
This cover dates from iPad 2 launch - have these covers changed during their lifetime or are they still the same inside and out? I know they have not changed specifically for "new iPad" but I read one forum post that claimed the inside material had changed.

Looks to me like the leather covers might be less resilient - I saw one only about six months old that looked very shiny and polished inside, like worn suede.