The only thing a lifetime ban would do is make the anti doping agencies raise the standard for what it takes to catch someone since EVERYONE would take them to court. Like the death penalty, lifetime bans would be VERY expensive to prove and make stick.
I think they should go the other way. 6 month bans which drop to 0 months if you can help them catch someone else.
As for paying the money back, that isn\'t going to happen. All dopers will just spend the money immediately. I think they should set up prize money as annuities so it takes winners a long time to get the money. If they are caught later, most of the money is still there, to be handed to second place. For a $50k prize you could buy a $150-200k annuity that paid over 20 years. It would also be good publicity if it sounded like the prize money went up 3 or 4 fold.