Well, first of all title and OP question are kinda different so I'll answer both.
How do you deal with the knowledge that your experience on Earth will end?
In my honest opinion I do not care, everyone dies at some point and if I could live forever I wouldn't really want that, the though that living on this planet for over even 100 years kinda makes me cringe. I know this isn't a very detailed statement, but meh.
How do you deal with death?
Now this is completely different. Basically this is saying how do you deal with death around you. For me after 18 years I have experienced some losses over my lifetime. And I have learned to accept death, people die, wether it be natural, murder, etc. There is a reason we are humans, animals, living organisms, that at one point or another die.
The first person I ever personally knew and died was my uncle on my mother's side, and of course I was suprised, and not happy about it, but I dealt with it, just like the rest of the crap that I've gone through. So yeah. Those are my opinions on this whole thing.