How to increase the battery life forSamsung Galaxy S Duos S7562 Smartphone and other

new Android Smartphone device the current smartphone which i am having. I am a gaming addict for android smartphone and i love to play games online. Problem which i have been facing for a quite while is the battery life for my phone.

Just in a game play of around 2-3 hours...it starts showing battery low. So, i would like to know if there is any application through which i can recharge my battery or double my battery power.

Please help.