I have been using a Morrell Yellow Jacket broadhead target for a couple of years now and have 2 holes that are just about shot through...
While at Lowes Hardware yesterday, I picked up a can of foam insulation...I went home and filled these holes with the insulation...

After work today, I cut off the excess foam and shot 6 arrows through the repaired area...The foam stopped the arrows and were pretty easy to remove...I think I can make it through the season with this target...