Efficient way to implement some services(Java Beans) when they have a shared database

we have two projects as proj1 and WS. our platform is JavaEE. These projects have a shared DB so they can do anything with data at their part. For now we would like to implement another web service in the WS project. meanwhile our projects are running on different clusters so they are not local for each other. So the problem is If we implement the service in the WS project then our remote calls are OK (calls from out) but calling from proj1 will have some network and performance costs, against local calls, for us. On the other hand implementing another function on the proj1 will duplicate codes and we should be care about any changes in a WS implementations. I am confused to choose a way to implement this service. I will appreciate any clue and guide.