Yes its possible to fix the battery balance leads on the battery. .I have had to do this a few times already.. If your soldering skills and soldering iron are up to the task.. you have to carefully open up the battery, just at the top where the leads are.. once open you will see where the wire broke off from the battery tab.. using a hot soldering iron tin the old wire and reattach.. One word of caution however.. don't short out the battery and please wear safety glasses when doing this.. these batteries are capable of serious injury and fire if shorted out.. If you are the least amount uncomfortable about doing this, you can charge the battery thru the discharge lead, but you may have issues down the road... Once finished with the battery, use strapping (filament) tape to finish the battery..
On a side not.. if your leads are breaking, you have to address the issue as to why.. do you have excessive vibration in the heli or are the wires undergoing some kind of strain on the heli? they don't just fall off.. mine was from a slight vibration that I thought wasn't a big deal until I started having battery and motor connection problems..