I do not blame you. I would assume only the bottom feeders without a great pick set would want a redraft. However, there is no fair way to let those players into the draft.
The other possibility is that you lock all of those players for one season, but then everyone just plays for draft picks.
ETA: Redrafting would definitely defeat the purpose of a keeper. At the same time, you cannot fairly contract teams though.
This post was edited on 10/1 at 9:43 pm