In case the connection to the LDAP service has dropped out for some
reason, this function will reconnect, and re-bind if a bind has been
attempted in the past. It is probably most useful when the server list
provided to the new() or _connect() function is an array rather than a
single host name, because in that case it will be able to connect to a
failover or secondary server in case the primary server goes down.
This method just tries to re-establish the current connection. It will
sleep for the current backoff period (seconds) before attempting the
connect, and if the connection fails it will double the backoff period,
but not try again. If you want to ensure a reconnection during a
transient period of server downtime then you need to call this function
in a loop.