Chasing moving object

I would like to let my hostile character chase a friendly character for some time.
Because hostile characters cannot walk through doors, I usually create paths for them like this:
seeker.StartPath(seeker.transform.position, target.position, callback, graphMask);
however, for chasing an object I believe the easiest way would be to just set the aiPath.destination variable frequently. But if I do that I have no idea how I can constrain the paths to a graph mask.

Also, I realized that the character wouldn’t move anymore when calling seeker.StartPath() the next time… do I need to somehow clear the aiPath.destination?

Basically, the question is: what is the best way to chase a moving object while using a graphMask?