OK so if your battery keeps dying, that can definitely produce some difficult problems with motorcycle reliability. The most common cause is an old battery, remember that most liquid batteries are only good for 1-2 years, so if you can't remember the last time you changed your battery, it just might be reaching the end of its life.
Another common cause of a battery which fails to recharge is poor connections. These connections run from your negative terminal to the frame of the bike, and the positive terminal to the starter solenoid, and then to the rest of your electrical system. Take them apart, scrape them down to the bare metal with a piece of sandpaper, the edge of a knife, etc, and then reconnect tightly.
After you have done this its time to see if you are in fact charging. To do that, take a volt reading of your battery and see where it is, it should be somewhere between 12.3 and 13v. Now start the bike. Some smaller bikes will not charge at idle, and you will actually see the voltage drop. But once you rev up above 2000rpms, you should see the volts rise above 13.5. If it gets above 15v that is actually harmful for your battery and might mean you have a bad regulator/rectifier.
