CITI Refresher. In order to maintain CITI certification, everyone is required to complete the CITI Refresher course every three (3) years after initial certification is obtained. Completion of the refresher modules can usually be completed in less than two hours. New employees must complete the required modules and obtain CITI certification within 90 days from date of hire. 2  Members of the human subject research team, including the Principal Investigator (PI), must have current certification.