I have an ornamental yellow leaf flowering bush that was eaten bare by grasshoppers despite the Neem oil I applied. It was bare by mid-summer, so I don't think it was able to replenish its roots. I love that bush that I planted when I first moved into my newly built home. I have lived here now 31years & had never seen such a plague of hoppers. I used Neem oil as I did not want to harm the toads & birds that might eat some of the treated villains. I didn't get good results from the Neem Oil & now understand it is most effective when the hoopers are less than 1/2 inch. I will definitely apply the oil much earlier next year. Thank you for any suggestions you might have.
Unfortunately, without knowing the species, I can't give a very straightforward answer. Many species of shrubs and trees will come back from heavy damage. Still, there are many that are a lost cause. It is always worth trying to save it, though. Since there are a few factors that might be working against you, there is little that you can do. Providing the best conditions possible will give it a better chance.
For good measure, I would test the soil for deficiencies or pH imbalances.
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/testing-soil.htm
This will help you to combat the grasshopper issue:
https://www.gardeningknowhow.com/plant-problems/pests/insects/grasshopper-control.htm