Hmm.. actually i don't think you can.
As far as i remember if 1 and 2 letter, and some special word domains drop they are not released for reregistering..
Something about Icann wanting to keep them for extra tlds lik .uk.com or something like that.. don't remember the full reason, but it was something like that..
So if you got a 1 or 2 letter domain you better be damn sure to pay that renewal
