Any person holding a current valid license, permit or certification may renew such license, permit or certification for the next year without taking another examination, unless the license, permit or certification is not renewed by April 1 of any year in which case such licensee, permittee or certificate holder shall be required to take another examination: Provided, That no person holding an expired license, permit or certification may engage in any activity for which such license, permit or certification is required until such license, permit or certification has been renewed. Any person renewing after January 15, of each year shall pay a penalty of twenty-five percent of the established license, permit or certificate fee. A penalty of fifty percent of the established fee shall be levied after February 1 of each year. Persons delinquent after February 1 shall be so notified.