IF your Library is intact (metadata.db and all, all you need to do is configure the plugin to use the (still) existing columns.
Most PI store their configs in the Calibre Configuration folder, all the data is per Library. (Note taht some PI do keep some configs in the metadata.db because they are Library specific)
keep a backup of you config folder. when you restor, you will just get a notice you PI's may be (really) out of date and you simply update those as usual.