Tough question with several answers.
Several things are involved: time of season, how hungry are the deer and whether or not the plant has had enough time to get established.
If early in the season and the crown isn't chewed up, the roots should be ok and continue to do their thing. It's possible that a second flush of leaves will appear. But, if the deer are really hungry, they will keep coming back to much on the new growth.
If the plant hasn't become established, it may be pulled out of the ground while being eaten. I have yet to meet a deer, or squirrel, that will replant something that was pulled up. If the plant is pulled out of the ground, and you notice it right away, replant it. If you don't notice it, it make get confused and go dormant. If early in the season, replant in a pot and keep an eye on it.
There are a number of products on the market, both organic and not, that can be put around the plants to keep the deer out. Check with your hosta guy at the nursery and see what he recommends.
Something that I've had to resort to is actually putting a fence or cage around the plants. This will depend on the terrain and plant location as to what will work best. I use a combination of things. For example, the tall plastic coated wire plant support panels. They are usually 3 panels connected to each other. You can use a set to encircle a plant or several sets to put a barrier up. Keep in mind that deer can and will jump the barrier if they are able to see enough space for landing. And they can jump high.
Another, less obvious deterrent is nylon net or tulle. We had a fabric store close earlier this year. I literally bought all of the black, brown and dark green net they had left. (The dark colors won't stick out like a bright beacon in your gardens.) Use one or more pieces to lay over the plants and anchor the ends in some fashion. When the deer stop by for breakfast, they will get a mouthful of netting and wonder what's going on. After a couple of tries, they'll move along.
Incidentally, I have also started to use the netting to cover the ground after planting bulbs and seed. It keeps the squirrel and chipmunk from digging things up while still allowing free circulation of air and water.
