Unfortunately.....from what I understand.....when you delete an app. The device deletes the app and all the related saved content within the app's "zone" of data. So, yes it is gone.
When you... Sync your device and "back-up" the info for the device...(apps, settings, orientation of your icons, the content loaded on the phone like music in iTunes and stuff that you sync from a computer and the way all the data is handled for that date. ...etc.) is saved not the extra additional personal content...(pictures, recordings, works in progress....) the primary things are "backed-up" so if the device fails it can be brought back to the way it was...a bummer about lost work but your device is working again.
A "restore" is the function that puts the device back into one of the saved "back-up" states....that was a working incarnation of the device at an earlier date.
It is up to the user to pull the additional documents and works in progress by the share methods and app content area in iTunes when you sync.
Sorry to hear.