Close suspended apps. Double click home button, the screen items should raise and there is an extra row of apps appear at the bottom of the screen. Press and hold one of the apps that appear at the lower part of the screen (these are the apps that were suspended). When they start to shake/wiggle, press the red X on all of them to close them.
Check your email settings and make sure "push" is enabled and the "Fetch" is set to less frequent options
Your screen might be set to 100% brightness comparing with your previous usage settings
If you don't use any Bluetooth device with your iPad, you could turn the Bluetooth off by going to Settings > General > Bluetooth. That saves some power.