Propagating Editor data in cooked builds

I created a box component in C++. I have a FVector variable, mExtent, which sets its size in the constructor. mExtent has a default value. Now I want the mExtent to be set by the editor for every different instance of this box component. I have overridden PostEditChangeProperty so that if I change that variable in Editor, I can see the change live. But how do I propagate that change to the cooked version. It seems the value modified in editor doesn’t get saved in the umap for some reason.
Any help?