Hello,

How did you upgrade the catalog to 9.2.1?

If you use CatalogUpgrade tool to upgrade the catalog to 9.2.1, the tool will reindex whole repository automatically. Thus, you don't need either "reindex the entire repository" nor "only reindex the documents which were indexed earlier". See https://www.laserfiche.com/support/webhelp/Laserfiche/9.2/en-US/AdminGuide/LFAdmin.htm#Installation/LF_catalog_upgrade_wizard.htm for detail.

If you delete catalog of 8.0.3 and create the catalog of 9.2.1 via LF Admin manually, then it depends on your index policy: If you only want selected documents searchable, you can choose "only reindex the documents which were indexed earlier"; if you want whole repository searchable, you need to choose "reindex the entire repository"