You can use parts of Xcode to analyze what's up with your app. I haven't done this myself but I'm finding the following suggestion online:
Apple's own documentation on monitoring battery usage
There are also ways to monitor network activity (like Wireshark) if you suspect that might be the issue, though I'm not sure how those work together with Apple. Maybe someone else can elaborate on that part.
A usual suspect for battery drainage is client side polling. Check if the App Events widget is used in your app. Timeout events will stack up if used on several pages and constantly request the server for data, thereby draining the battery quickly.
Thanks for the suggestions! Just to clarify, our app is actually web-based and accessed through an iPad browser rather than being a standalone iPad application. Any insights specific to web-based apps on iPad browsers would be greatly appreciated!