You can update physics mesh using this line of code!:

[c.owner.reinstancePhysicsMesh()](https://docs.blender.org/api/blender_python_api_2_60_1/bge.types.html#bge.types.KX_GameObject.reinstancePhysicsMesh)

Note: This only works with triangle mesh bounds


  [1]: https://docs.blender.org/api/blender_python_api_2_60_1/bge.types.html#bge.types.KX_GameObject.reinstancePhysicsMesh