The Dominican Republic has set up a page, in English, that guides you through the process of extending your stay in the country for up to 4 months. It can all be done online.
migracion.gob.do
STAYING EXTENSION - DIRECCIÓN GENERAL DE MIGRACIÓN
Authorize foreigners interested in prolonging their stay in the Dominican Republic for more than 30, through an extension that can be extended up to 120 days.
migracion.gob.do
