law: 37.Enhanced penalty after previous conviction.-
  If any person who has been convicted of any offence punishable under this Act is again guilty of an offence involving a contravention of the same provision, he shall be punishable on a subsequent conviction with imprisonment which may extend to 3[one year, or with fine which shall not be less than ten thousand rupees but which may extend to one lakh rupees, or with both]:
  Provided that for the purposes of this section no cognizance shall be taken of any conviction made more than two years before the commission of the offence which is being punished.