Anyway to un-shrink a wool sweater?

I washed my favorite merino wool sweater in cold water and hung it up to dry. Upon putting it on I discovered it shrunk about 5%, making it just a little too short above the waist. Is there a way to de-shrink wool or should I donate it to the People With Small Torsos Fund?
(disclosure: the tag said “dry clean only” but I’m too lazy to get myself to a dry cleaner and figured cold water would work.)