Question About Updated Models in Collections

I've been using the collection tool for several of my models, but collections don't seem to update when I update the included models. I.E. Model A is available as .3ds and .obj, but Model B is only available as .3ds. Even though I add an .obj format to Model B, the Collection still shows that .obj is unavailable for that model. Is there any way to change this? Do I need to delete and recreate the collection or is there an easier way to update them?