Put your ff-number in when you fly award tickets too - miracles do happen sometimes (average about 1 out of 10).
Chances for miracles improve if you have "only" upgraded your ticket (from eco to business) and later on changed at the gate to an earlier flight (normally no charge for that on the same day) a good friend of mine guesses that in about 1 out of 5 he will then get credit for the upgraded class ... and he doesn't mind - would YOU?