Wireless sensor networks are usually randomly deployed in the monitored region. This initial deployment does neither achieve area coverage, nor ensure network connectivity. Thus, a redeployment algorithm has to be applied in order to meet these two requirements. In this paper, we overview existing centralized redeployment algorithms such as virtual forces or particle swarm optimization category, as well as distributed algorithms such as Distributed Self-Spreading Algorithm, Force based Genetic Algorithm, Mass-Spring Relaxation Algorithm, unified Scheme for Deployment and Relocation. We then discuss some open issues related to algorithm convergence, assumptions about the initial knowledge available like the initial topology, number of sensor nodes and obstacle positions.