The deployment is one of the stage while creating a wireless sensor network. A deployment may not reach some requirements for sustained and reliable operations, even though some redundant sensors are deployed. Improving the deployment by adding some sensors is an efficient way, which is treated as the incremental deployment problem. A problem named Minimum Incremental k-Coverage in a two-dimensional continuous space is formulated. Some definitions and theorems of coverage and adding target positions are derived. A heuristic approach to this problem is proposed and its performance is evaluated through extensive simulation-based experiments.