If the Scout is out of range, the Knog app will show ‘Disconnected’ . Your Scout will remain armed, even if you are outside of Bluetooth range. Once you are back within range, the connection will be reestablished and you will have full control of the Scouts functions again via the app.
If the Scout does not reconnect when you are back within range, you can try force closing the Knog app by swiping up on your phone to open all running apps, then swipe up again on the Knog app to completely close it. Then reopen the Knog app and this should reset the connection.
For information regarding the expected Bluetooth range of Scout, you can head here.