design and routing for setting up multiple environments with LTM

Routing in the DMZ is an now the issue that I'm not sure how to handle properly

If I have Vlans with different IP networks for each different environment but I only have interface on my router to get our of my DMZ, what is the correct was to solve this? Do I add additional interfaces to the DMZ router or handle this differently?

Previously I'd use 192.168.1.1 as a route for Route domain 1

The VIP Vlan in the DMZ was on the 192.168.1.0/24 network previously. Now that I have 192.168.2.0/24 (Dev VIP ) and 192.168.3.0/24 (Staging- VIP) I obviously can't connect to the 192.168.1.1 router. So do I add additional interfaces on my router or handle this a different way.

ON the internal side I just add an IP address for each vlan and then set the route for each route domain to that Gateway.

Appreciate any help.