can I un-shrink wool?

[e_p]

I don't know how I did it, but I've somehow shrunk DHs favourite and warmest winter jumper. It's 100% wool and was reasonably expensive too...we don't have a dryer and I generally cold wash, all I can think of is that I accidentally put the washing machine on a hot cycle.

Anyway - this may be the dumbest question ever asked...but is there a way to un-shrink it?