This might not help if you don't have the charging adapter and can't get in touch with the manufacturer.If all else fails you may be able to take it to a battery store and they could probably make you a custom battery for it.
http://www.law-17.com/instructions.html
The Battery When the laser is bright for a moment then goes dim, it means the battery needs to be recharged. Do not de-charge the battery! Use a 9 volt alkaline battery with the charging adapter suppled with your laser. Plug the adapter into the charging port at the bottom of the forearm ( se illus.). Do not activate the laser while charging! Remove adapter after five minutes. Ten Minutes maximum A good Battery will provide several recharges. If your battery fails to take or hold a charge, return the frame to the Factory. Do not attempt to change battery yourself.