Ex-Employees who are also Ex-Applicants Now Re-Applying

We employ students every year and they all applied via iRecruitment last year. When we hired them, we end-dated their personal record. When they left, we did nothing other then end their employment. Now many of them are re-applying for new student positions we are available.  However, they are not able to re-apply. They try to apply as a former employee and their password does not work OR if they request a new password, it doesn't send them a new one (it doesn't recognize them). Long story short, I don't believe we are handling applicants correctly when we hire them