OK, so this should still be a feature in the Android client - try to reconnect periodically or when the network changes (i.e. wifi->cell or cell->wifi). Please add!!

In the mean-time, I created a workaround:
You need:
1. A rooted device.
2. Some programming/hacking experience as my script will probably need some adjustment to work on different devices/ROMs.
3. Automagic (Android play store $4)
4. Download the EAP test build of Automagic from their forum.
5. Use my "Flow" (Automagic's name for their script) which you can get here
http://automagic4android.com/forum/viewtopic.php?f=5&t=3040&p=6392#p6392My Flow detects a change in Network state, runs Neorouter, and clicks the Sign-in button. Note: No support provided by me (see #2 above

I hope this helps someone!
Mark