i had the same problem even on normal use i would only get like 10 hours max on normal use and now i get more than 14 hours and thats listening to music, checking my emails and surfing the net but i do point out that the new Face Book Beta app has been reported to waste a **** load of battery even when not signed in and background data turned off, i deleted the app and the problem had disappeared. Metro Tube wastes a **** load of battery as well and as well as playing games, also turn off automatic screen brightness and set it to 'low' and leave it there as it requires more battery on auto screen brightness due to constant light changes.
hope this helps ^.^ i have a Lumia 920 and i been through this difficult time, be strong brother be strong