The SDcard can be backed up by removing it from the IoTaWatt and backing up on a general purpose computer. Not a convenient everyday solution.
SDcard wear is much lower with the current firmware releases and under ordinary circumstances should not cause failure. The best approach to regular backup of your data would be to upload to influxDB or Emoncms.
The config file is currently backed up in the SPIFFS file system on the ESP8266 and can usually be recovered if rebuilding an SDcard.