Keeping the Search Index up to date is accomplished by running Disk Refresh, Create Index or Update Index jobs found in the Titan Administration module. Links will be accessible for existing Create Index and Update Index Jobs in Smart Search Admin section. Clicking the link will take you to the job in Titan Admin module. If links are not listed it may be due to user access limit or jobs were not configured yet.
*Remember to verify your Pages, Files, Data have the Property Index checked to be included in the desired Search Index.