Wireless sensor networks, like other computing platforms, require software updates from time to time due to software bugs, new functionality, better understanding of the surrounding environment or new applications. Physically connecting to and reprogramming each node is usually not feasible and often impossible. A number of wireless code distribution and reprogramming techniques have been presented. In this paper we present a novel technique to efficiently update any nodes that were lost during programming periods. Our experiments demonstrate a 57% decrease of bytes sent over the air when updating nodes that previously missed updates.