How to restore shading of a modified mesh?

At the moment I’m working on a terrain LOD system. I have to use Python to modify the geometry of the terrain (for display and physics) with the side-effect that the shading stays flat, due to the normals not been recalculated.

As far as I know normals cannot be calculated in game, but I wonder if there are any tricks to solve this issue. Maybe a shader?

Thanks.

Bumping this, hoping there would still be someone who could give an answer.

You have to recalculate the normals of the mesh and set them for each face and vertex manually.
There was an example for this in the resources forum somewhere.

I think its vertex.setNormal(xyz)