We present an auction-based method for dynamic allocation of tasks to robots. The robots operate in a 2D environment for which they have a map. Tasks are locations in the map that have to be visited by the robots, in any order. Unexpected obstacles and other delays may prevent a robot from completing its allocated tasks. Therefore tasks not yet achieved are rebid every time a task has been completed. This provides an opportunity to improve the allocation of the remaining tasks and to reduce the overall time for task completion. We present experimental results that we have obtained in simulation using Player/Stage.