Baked Lighting

Hello,

I am trying to archieve baked lighting in my scene. However, when I imported the models, I didn't enabled the generate lightmap UV's. I have elready created the prefabs, and set up my scene. After that, I have enabled the to generate them in the model. But if I try to create the baked shadows, no shadows appear.

Is there any way to update the prefabs, or I have to create new ones?