You should be able to redeploy the app.  no need to wipe the device.  

That's good to hear. But how? The scope of the app is "all devices" and "all users". How do I get the app back?

An inventory update should reinstall the app. Is that not what you're seeing?

Nope. Inventory update didn't do a thing.

I've wiped the device now, so l call it a day. Thanks for the help all...

remove all devices and users from the scope will uninstall this app, save and wait for a while. and then add the device to the scope again, the app will be reinstalled.

by the way, target to the devices is fine, you don't need to add users to the scope.

Simpler: Exclude the affected device from the Self Service Mobile deployment, save to newly assigned only, remove the exclusion, and save again to newly assigned. The install command will go out to the device again.

That's clever! I'll use this next time.

So other users won't be affected.

If for whatever reason that doesn't work, also know that nothing is stopping you from creating an additional instance of the app using the same license pool, but different scoping.