When an exhausted skill die is removed from the cooldown track by your Recovery step or another effect, you recover that die. Place it in the correct slot in your attribute rows. That die is immediately available to use. When a status effect die is removed from the cooldown track, return it to the supply.
A drained die can only be recovered by an effect that specifically recovers drained dice, by visiting an inn during a town encounter, or during the Adventurers Rest step of the End of Day Phase. Drained dice are discussed further under Resolving Skill Abilities.