Changing GPS location of Apple routers
There's a company called SkyHook that sells a wifi-based geolocation product to many companies, but not sure if Apple is one of them. It was a couple of years ago though. 

You can ask them to update their database here: http://www.skyhookwireless.com/submit-access-point. If Apple is doing their own geolocation services now, you're likely out of luck.

ETA: changing your (E)SSID probably won't do anything; the location services are more likely to use the BSSID, which is the wireless MAC address of the equipment.