adding dhcp addresses

I’ve inherited a small network with 60 users in a very quickly growing company. Their internal IP scheme is 208.235.195.0 with a subnet mask of 255.255.255.128. I know the scheme uses public IP’s, it’s a long story about getting cut off from their former ISP where everyone had public IP’s, and they added a router to do IP forwarding, so the IP’s are assigned by a DHCP server. with all the printers and new users, there are few IP’s left.

I need to add more capacity and need recommendations asto how to do this. changing the whole scheme would be ideal but it not practical in terms of time and manpower (ie, me), any suggestions?