The problem of configuration of Wireless Sensor Networks is an interesting challenge. The objective is to find the settings, for each sensor node, that optimise certain task-level QoS metrics. An existing configuration method is available for tree-based static networks. We extend this method to support a mobile sink. First, the routing tree is adapted to the sink's new location, after which the parameters of the nodes are optimised. Both algorithms are distributed and localised, and therefore efficient and scalable, and are able to flexibly trade reconfiguration cost (time and energy) for quality to match the demands of the application. Various options are analysed, and evaluated in simulation.