Any person who induces or attempts to induce any child to be absent unlawfully from school or who knowingly employs or harbors, while school is in session, any child absent unlawfully shall be guilty of a Class 3 misdemeanor and may be subject to the penalties provided by subdivision 5 a of subsection B of § 16.1-278.5 or § 18.2-371. Upon a finding that a person knowingly and willfully violated the provisions of this section and that such person has been convicted previously of a violation of this section, such person shall be guilty of a Class 2 misdemeanor.