Re-baking navigations by script???

Hello,
I am developing a game to where a room that has 4 walls with an open doorway on each wall gets instantiated and placed together side by side in a 3 dimensional grid (making it look like my game has endless rooms). I made my floor into a static object and baked a navigation system.

The problem I am having is that when the rooms instantiate, I can not 'instantiate' the navigation system along WITH it (for the multiple rooms), BUT, I was hoping there was SOME way to code a 're-bake' for my navigation system. Something like...

Navigation.Bake();

after my rooms get instantiated. Is there a way to 're-bake' everything during runtime?

Thank you.

 

I am fairly sure nav baking can Only be done manually.

 

I think not yet with Unity3Ds system, you could write your own or use some AStar solution from store, but it is in the road map https://unity3d.com/unity/roadmap

 

If they have Nav Mesh Obsticles, wouldn't it be a neat idea to invent an inverted Nav Mesh Obsticle at least (where it 'undoes' or 'cancels out' the Nav Mesh Obsticle)?