Routing Question

On a Linux work station I edited /etc/init.d/network and added at the bottom
just before the last "exit 0", the following

route add -net 192.168.100.0 netmask 255.255.255.0 dev eth0

when I restart the network (/etc/init.d/network restart) I get the message
"SIOCADDRT: File exists"

It works but is there a better place to be doing this???

Thanks

George