Moving Airport Network from one ISP network to another

I'm switching from DSL to FiOS. I'd like to reconfigure my existing Airport Express 802.11n network (three units, none hardwired to the wireless DSL router) to the new network. When I switch to the FiOS network, my desktop can see the original equipment router. When I switch back to the old DSL network, I can see the Airports.

When I go to edit the Airport settings in the Airport Utility, the new network does not show up. Is there anyway to force reset the Airports (e.g. wipe back to factory settings and then reconfigure my network)? Do I have to hardwire one of the Airports to the OEM router?