As the Netgear wireless range extender has been already setup previously with the old router, so, the first thing we have to do is to rest the Netgear wireless range extender. Then only we would be able to set it up with new router. To rest the Netgear wireless range extender we have to look for the button called reset on the extender. It could be on the side of the extender or it could be underneath of the extender. So, by just hitting on that button we could reset the Netgear wireless range extender.
http://my-wifiext.net/geniesetup.html