Resetting SSID and password for WIFI connection?

Is there a method for changing the wifi network the unit connects to, or do I need to re-flash the microcontroller to start over and enter a new wifi SSID and password?

Easiest is to disable the current WiFi, restart the sensor. Then because it does not find the old WiFi SSID it will open the hotspot again with which you can connect to and enter the new WiFi credentials.