Once a student has been accepted to an educational institution for full-time study they can apply for a Student Pass.
This pass enables the student to remain in Singapore for the full duration of their studying, thus renewal is typically not required. More specific application requirements differ by specific schools and can be found at http://www.ica.gov.sg/ . It is important to note that if one simply desires to take a short course, which is less then the duration of stay granted on the Short Term Visa, a Student Pass is not required and one can simply take the course.