The increasing prevalence of networked devices brings ever more opportunities for delivering content and services to users that result from situated interactions between computational devices in their surrounding environment. Resource discovery, a vital component in this process, becomes challenging in such an open, dynamic and distributed setting. Building on earlier work that outlined a novel semantics-based approach to resource discovery in such environments, this paper provides a general solution to incorporating application-specific contextual factors into the resource discovery process, and proposes a mechanism to support the runtime evolution of resource discovery tasks in a mobile setting.