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 the first day of April 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 the fifteenth day of January 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 the first day of February of each year. Persons delinquent after the first day of February shall be so notified.