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A failed node can create coverage and connectivity holes in a sensor network. In order to maintain network effectiveness, failed nodes should be replaced. A new concept, called policy for failed node replacement, has been given to improve the network operational lifetime by repairing network holes created by failed nodes. These policies can be incorporated in any topology control algorithms. In the Directed Furthest Node First (DFNF) policy, an active node repairs the hole using one of its deactivated neighbours, selected based on distances from the hole. Weighted Directed Furthest Node First (WDFNF) selects replacements by considering both the distance and direction of a node. In Best Fit Node (BFN) policy, all the active nodes adjacent to a coverage hole participate in the replacement procedure. BFN can efficiently handle the network holes with higher computational complexities, however, the simulation result shows that DFNF and WDFNF can maintain the same network lifetime as BFN when network condition was extremely dense.