A critical problem of wireless sensor networks is the efficient handling of the nodes energy under the target coverage constraint. The sensors are randomly deployed in the field covering a set of targets. Due to the randomness of the deployment some targets are covered by a few only sensors. Thus, the maximum achieved network lifetime is upper bounded by the energy of the sensors that cover the most poorly covered target. To tackle this problem one could move some sensors to these poorly covered areas from areas that are covered by many sensors. In this paper we present centralised and localised solutions that can be used to redeploy the sensing nodes and balance the amount of energy between the sensors that cover each target. We simulate our algorithms and our findings show an over 100 % increase of the amount of energy of the sensors that cover the most poorly covered target in the network.