One major limitation in WSN is the lifetime of the nodepsilas battery. The aim of this paper is to overcome the power constraint in WSN by wirelessly charging the nodes using a newly discovered technique for single hop wireless energy transfer called Witricity. In this paper, we present new techniques for multi-hop wireless energy transfer. We specify the hardware a sensor node needs in order to wirelessly transmit and receive energy. Finally, we present a charging protocol for a WSN with flat topology and another for a WSN with clustered topology. Our results show that multi-hop wireless energy transfer can be done with an efficiency as high as 20% over 8 hops. The work in this paper is the first that addresses multihop wireless energy transfer in sensor networks and is the building block of our and other future research in this area.