Lightroom :: How To Re-create Same Collections In New Catalog

I recently converted all of my pictures to a new format.  I want to make a new catalog, identical to the old one, with the new pictures.  I imported everything, but I don't know what to do about collections and smugmug folders.  I still have the old catalog, and all of the old pictures.  But I need to reupload all of the new pictures to my smugmug site, same as before.  So, I need to recreate every collection and add the new pictures like they were before.  Is there a faster way to do this?  Can I use my old catalog to somehow recreate the collections?  I still have the old catalog, and all of the old pictures.  All of the filenames of new and old pictures are identical.  I also have a few collections that I would prefer not to manually recreate.