In a keeper league you're allowed to retain a few players from the previous season to play for your squad in the upcoming year. If this sounds like a good option have your commish open the "LM Tools" page and select "Yes" from the dropdown menu. They'll be given an option for how many Keeper slots to make available and also when the list locks (when you need to finalize your keepers for the next season).
If your league switched to ESPN from a different website have your commish go into the "Edit Team Rosters" link and manually assign the Keepers to their appropriate teams BEFORE your draft occurs. If your league has draft pick trading make sure you trade the picks before the keeper selection deadline.