def refresh(self):
        """ refreshes a service """
        params = {"f": "json"}
        uURL = self._url + "/refresh"
        res = self._get(url=uURL, param_dict=params,
                           securityHandler=self._securityHandler,
                           proxy_port=self._proxy_port,
                           proxy_url=self._proxy_url)
        self.__init()
        return res
refreshes a service