I would suggest that your client should simply reconnect to the server
whenever it detects that the connection has been lost. Any distributed
application that hopes to be robust should do that anyway.

If your connections are stateful, the server should remember the state
of the client it disconnected. Upon reconnecting, the client can
request that the previous state (if any) be resumed, otherwise the
server can discard the saved state at that point.

Another idea is that you should be able to detect wakeup without
outside help. If you note the time you send each alive event, and
discover that the previous one was "long ago", then you can assume
that you've been asleep for the interim.

/gordon