Fixed issue where if the server was down for a time, then came back up, the plugin would be unable to successfully send data unless the service was restarted.
This was caused by our Duration being greater than the allowed maximum, and never being reset.
This should fix the issue described in https://support.newrelic.com/tickets/55385 and https://support.newrelic.com/tickets/55367?col=2117133&page=1