Have you tried disabling unnecessary power-guzzling thigns like background tasks, NFC, turning Location off and other measures? Basically anything in the Settings that you feels is not needed to constantly sync online etc etc.
also have you tried performing a soft reset (pressing the volume down and the power buttons together until the phone vibrates), and also checking that your SIM card is cut properly to microSIM size and doesnt have any damage.
I also would check that you have all the Nokia updates in the Store such as Extras + Info, feedback, access point, Network + etc installed and updated to the latest version.
If none of the above works, then perform a backup of all your personal data via PC and / or SkyDrive, and perform a hard reset (go into Settings > About > Reset your phone).
Failing that, you will need to take your phone back to your point of purchase for a replacement, and if they are being less than helpful, then visit your local Nokia Care point for them to inspect: http://nokia.com/support
A few people are not having any issue with the battery performance on their Lumia 920 at all. I believe the reason could be that they use their phone too much and think the batttery drained off so quickly because of the heavy phone usage.
A important note for all the Nokia Lumia 920 owners - When I say battery issue, that does not mean it happens every day or 3-4 times a day. It can happen after 2 days or even 3. For those who believe their phone has no issues please do not use you phone for a day or two, turn off eveything (Bluetooth, WiFi, NFC, Data Connection and GPS) and just send some texts and make 2-3 calls and see the results yourself.
I have used two different Lumia 920 and both showed poor battery performance. The battery issue on the first phone started since day one while on the second phone it started after 5-7 days with a gap of 1-2 days, which recuded later on.
All that you are asking to do (skydrive, upddates and other stuff). I have tried doing all that, plus turned off everything that could eat up the battery and even rest the phone more than twice. Trust me that really did nothing. Check your phone there could be battery issue with your phone as well, you might not have noticed it 
Waiting for a genuine reason and a solution from Nokia and/or Microsoft.
