A button/link on the Administration page that causes Confluence to remove and rebuild its indices from scratch, to spare customers having to do this by hand at the command line.

The simple approach is to remove the index directory, then trigger the "rebuild indices" process, but this renders searching unavailable until the indices have been built. If it's feasible, a less intrusive approach would be to build the new indices into a separate directory, say index.new, then rename the current index directory to something like index.old, rename index.new to index, then delete index.old as a final step. The renaming dance allows the fastest possible switch-over, so that the users don't have to wait while the OS finds and deletes all the files under the old index directory.