For one thing, you have your Exchange email app running constantly. It should be set to Push updates (the server wakes the app when there's email for it) or manual updates (it updates when you open the app), not constant polling, which kills the battery quickly.
For another, if you keep using the battery down to near 0% 2-3 times a day, you'll be replacing the battery every 4-6 months. Charge when it's down to no less than 40% (and let it charge to 100%). The battery doesn't care whether that's convenient for you or not. Constantly discharging a battery almost all the way will give you about 300 charges before the battery fails. Charging it at 40% should give you about 1200-1500 charges.