Laptop shuts off before battery even gets low?

I have an HP laptop, and recently when it is not plugged in it will shut off randomly. It would shut off at maybe 30-40% battery life. When it was newer it would shut off on the brink of the battery actually being empty. When it would die at 30-40%, I would try to turn it back on and it wouldn't. Its as if the battery has actually died, when it hasn't. What can I do to fix this? This laptop is only about a year old now.