Hi,
Can you spot any root-shoot on your tree ? Since it does die back , is it multi-trunked from the soil line ?
If so, take only one root shoot to a pot of size like 4 or 5 gallons. Protect that pot in the garage every year - you're in Zone6.
Next year, bury the pot in the dirt when the weather and the tree allow.
Did your tree die back to the ground this very last winter ?
Do you have a pic of the tree ?
I use the 80 liters /20 gallons trashcan method as a winter protection . Look for my post with pics on that method on the forum.