LPT : Restretch a shrunken wool shirt

I've tried this method yesterday with a shirt that went from a large to a small size back to a large and I can confirm it works.

Soak your shirt in water mixed with conditioner while pulling at it, stretching out the fabric.

Now soak it in warm water for about 10-15 minutes but don't wring out the water afterwards; instead, hang it to dry on a hanger over a bucket or in your bathtub on the showerhead. The weight of the water will stretch it out some more over time. A couple hours later you can see if the fabrics have been pulled appart in a satisfactory fashion, otherwise you can go by and again for the final stretch.