When you say "update the wifi" do you mean you want to chance the WIFI hardware? If you do then the only way to easily proceed is make sure you give the new WIFI the exact same WIFI NAME and PASSWORD as the old one.
If you are however trying to change the name and password for your wifi I'm afraid you are out of luck. Please have been complaining about this for years and Google has never come up with a way to let you re-add the cameras if those codes are gone. Maybe people here have learned over the year to write them down or snap pictures of them when they are new.
