In order to renew your tourist visa, you only can do that at German Embassy in La Habana, located at Apartado St. 6610. You can get in touch with the embassy by telephone: (+53 7) 8333188 or going directly to the embassy. The attention hour is Mondays to Fridays from 9 am to 12 pm. They attend for emergencies the 24 hs (only German citizens)