Factory Image for Google Nexus 7 LTE will help you restore Android 4.3.1 on the slate
The new build is JLS36I and so far, no other Nexus device has had either the update or the factory image. Don't expect anything exciting with Android 4.3.1 outside of a few bug kills and the usual stability enhancements. The fun begins with the Android 4.4 KitKat update which should be introduced along with the LG Nexus 5 later this month. One early rumor had October 14th as the date when both the phone and the latest Android OS build will be introduced.
source: GoogleDevelopers via AndroidCentral