You can try to jump start it but I wouldn't recommend it. Once you're able to charge a dead battery and get your bike started, it won't hold it's charge as long. Even if you ride for an hour getting the revs up, you may have enough juice to crank the engine twice if you let the bike sit for a day or two, but after that it's dead again.
You're better off just buying a new battery. You can get a new battery at a Wal-Mart or K-Mart for about $30.
Same thing happened to me 6 years ago. I used a trickle charger, got it started, rode it for awhile and then it kept dying every other day. After a full week of trickle charging, the battery was completely dead.