This paper proposes a scheme for enhancement of network Lifetime using MObile Clusterheads (LIMOC) in a wireless sensor network (WSN). The low energy, static sensor nodes sense physical parameters and route the data to the highly energy-rich nodes called ClusterHeads (CHs) which are mobile and can transmit data directly to the base station (BS). A collaborative strategy among the CHs increases the lifetime (hence residual energy) of the network further. Simulation has shown that residual energy of the network can be improved by 45% by making the CHs always move towards the event in an event-driven network. For general cases, increased energy savings is obtained by making the CH move towards the center of equilibrium w.r.t. to both the total residual energy and data flow of the network.