How about 'ip virtual-router 1 priority 110' command?
When I checked the command with below basic config,
'ip virtual-router' configuration is overwritten.
I don't know the impact of production traffic since I don't send any traffic.
So, I suggest to configure it after office hours.
CSS11503-A(config-circuit-ip[VLAN774-192.168.74.200])# show run cir
!************************** CIRCUIT **************************
circuit VLAN774
ip address 192.168.74.200 255.255.255.0
ip virtual-router 1 priority 110 preempt <<==
CSS11503-A(config-circuit-ip[VLAN774-192.168.74.200])# ip virtual-router 1 priority 110 <<==
CSS11503-A(config-circuit-ip[VLAN774-192.168.74.200])# show run cir
!************************** CIRCUIT **************************
circuit VLAN774
ip address 192.168.74.200 255.255.255.0
ip virtual-router 1 priority 110 <<==
Regards,
Yuji