Stretching shrunken woollens, is there any hope?

[VanillaSpiceCandle]

Pretty much just that. I have a woollen dress that I risked putting in the washing machine. Unfortunately it has shrunk around 1.5 inches all over, but it's very even.

Is there any way of undoing the damage? I'm sure I read about using conditioner years ago but can't remember if it's fabric or hair?

Any tips or advice would be amazing as I've only worn it a couple of times and can't face giving it away - or losing that much weight!