The obligation to post your positions with the ESDS per the VEVRAA mandatory job listing requirement, applies to all payroll positions, with the exception of senior management positions, internal positions, and jobs lasting three days or less. If the intern position is on your payroll, then you have an obligation to list the position when you first hire the intern. Unless you have terminated their internship, and subsequently from your payroll, if they come back for multiple semesters, there is no need for you to re-post their position.