Restart a thing if connection is lost or if no new data within xx seconds

In JS Scripting there is a setEnabled() function you can use to enable/disable the Thing.

In the Marketplace there is a generic rule template you can install and use to call a rule of the own when the Things go OFFLINE.

If the Thing remains ONLINE and you can only detect it’s broken because some Items so updating, you can use the Threshold Alert rule template to again call a rule of your own when an Item doesn’t update for a given amount if time. Threshold Alert and Open Reminder [4.0.0.0;4.9.9.9]

The hard part will be mapping the Item to the Thing which isn’t so easy. I would add that as Item metadata.