A data refresh does not update existing user education records, but instead only inserts new ones. The refresh compares both school name and grad year for each user in the school's data file with any user education records the user has in Core, and if no exact match is found it inserts a new record. However, if the refresh does find an exact school name/grad year match it does nothing.
Tip: To avoid possibly creating duplicate user education records a school can instruct us to first remove them from Core so that the data refresh can insert a clean set.