It depends on when you're renewing. The way I read the regulations (
Section 946.290), your IDPH "approval" is good for three years. If you get approved but opt for a 1-year or 2-year card, you can go through an "expedited" renewal (until you hit three years) that bypasses the need for a physician's certificate or proof of residency. Once you hit three (3) years, whether because you opted for the 3-year card or after some renewals, then you have to go through the full application process again including producing a new certificate from your doctor.
Can anyone confirm?