LAN with two networks

I have a LAN with DHCP Enabled internet connection from one ISP, now for the same LAN we are connecting a Point to point Leased line connection by using a cisco router, How can i use the same LAN with these 2 networks. DHCP link is with 192.168.0.0 network range & Cisco is with 192.168.1.0 network range. Is there any solution without changing ips manually everytime to switchover between 2 networks