If you have been registered as a resident of Belgium in the past, you may also send your application for reregistration through the International Relations Office. Submit the same documents as if it were your first registration as a resident (see procedure residence permit).
However, you need to clearly explain in your mail to firstname.lastname@example.org that you were registered as a resident of Belgium before and in what capacity (student, ….).
Do not send in your application both through the IRO and through the immigration office in Deurne. That will only complicate matters.