I believe what you need to do is create in the registry a new DWORD32 value "SilentForcedAutoReconnect" set to 1, inside registry key:
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\NetCache\
It brings the synchronised folders back online automatically once the network is available again and saves you from having to reboot to achieve the same effect.
Very useful. Just one of the many wonderful hidden registry keys that really should be more exposed.