Admin/System Tools/Regenerate Abstracts
The Regenerate Abstracts button updates the timestamp in the archive's var/abstracts.timestamp file to the current time. This file is used whenever an abstract page is requested. If the current (server-side) cache for this abstract page is older that the timestamp in this file, then the abstract page is regenerated. This is better than regenerating all abstracts pages immediately. As a repository gets larger the time to regenerate all abstract pages gets longer and can put a high load on the server.
If you actually want to regenerate abstract pages use the bin/generate_views script.