Huiyan,
I really don’t mean to sound rude, but you should not be so paranoid about your hamster’s death. Eventually yes it will die, but there no reason to pine over it now. You should be thinking about how nice it is you have your hammy now and enjoy those moments. Spending all the time you have her worrying about when she will die will just make you more upset that you didn’t take the time to live in the “now”and enjoy her when she was here.
Hamsters live anywhere from 1 1/2 year to about 2 years on average. But many have been known to live as long as four years and I’m sure even 5! The first hamster I had only lived to be two years old before passing from old age. It seems as though you haven’t done to much research about hamsters. Why don’t you have a read over the hamster central website at
http://www.hamstercentral.com there are many helpful articles and things you can do to help your hamster live a longer life.
Please check this link below for many good articles on hamster health, from what veggies and treats to feed to hamster first aid kits and routine health checks and what to look for in an old hamster.
http://www.hamstercentral.com/healtharticles.htm