You can renew your Illinois CNA license through the Department Of Public Health either online or through the US mail.
Your CNA license will remain valid as long as you provide proof of at least 40 hours of supervised clinical experience in an accredited nurse training program to the IDOH Healthcare Worker Registry. You must also pass a written competency test if you have not done so because you were initially licensed in another state and were"grandfathered-in" to the Illinois medical system.
Following the national standard, the Illinois CNA license renewal fee is $40. In many cases it will be paid by your employer.
Links to important Illinois Nursing Regulations