In SDL Tridion 2011, there was an executable to rebuild the Solr search collection. How do we re-index search in 2013 ?
You can use powershell for re-indexing your search indexes.
Sync-TcmSearchIndexon powershell to reindex all publication
Sync-TcmSearchIndexwith a TcmRepositoryIds parameter containing list of publication URIs if you want to re-index a set of publication or a specific publication
Source and Reference: SDL Live Documentation