I just survived a horrific hail and wind storm approx 2 wks ago which shredded all my hostas also. I left them alone. By now most of the shredded leaves have turned brown and withered away. There is already some new growth appearing! There are still a few broken leaves hanging on; but it is very encouraging to see so much new growth so quickly after the storm. I had also thought about cutting mine down to the ground but am glad I did not. Hang in there and yours hopefully will come around too; esp. since you have until Oct. Good Luck!