The dynamic environment of hybrid mobile and fixed wireless networks used in military operations poses significant challenges in the efficient provisioning of software functionality to application clients. With their transient topology, the software services hosted on mobile nodes may become temporarily unavailable or the cost of transferring data across the network may become too high. To address this problem we have designed a placement technique that allows the dynamic repositioning of services within the network as it evolves. The technique repositions services in reaction to changes in network topology as well as in various system properties, such as service dependencies or the workload generated by application clients. In our approach we use a multi-layer model to represent a service-based software system embedded in a network topology. We apply constraint programming and its linear programming relaxation to solve the model to find where best to place or reposition the services. We evaluate the technique in terms of its effectiveness and cost under various simulated operational conditions.