Reconfiguration and self-adaptation are vital capabilities of sensor networks and networked embedded systems that are required to operate in dynamic environments. This paper presents an approach for software reconfiguration based on exploration of the design space of the application. The design space is represented by formally modeling all the software components, their alternative implementations and their interactions. Reconfiguration is triggered by monitoring the system and is performed by transitioning to a new configuration that satisfies the system constraints. The approach is demonstrated using experimental results for a representative tracking application.