Path replanning in path finding algorithms I'm working on a path finding algorithm for my thesis and I've gotten to a problem I need to solve where agents can replan their path if they need/have to. For example, if an agent is traversing across a corridor and then a barrier is inserted in, the agent has to replan because his old path is invalid. Another case is if the barrier already exists and the agent has to take a longer route, but while traveling, the barrier is removed and a significantly shorter route becomes available so the agent may replan but can still continue on his old path.

I have some ideas on how to work on the first case, but I'm at a loss for where to start for the second case. Does anyone know how other path planning algorithms deal with replanning, or can point me to any resources that can help me find some direction in tackling this problem?
The problem is known as the Canadian Traveler Problem.