—Whoever, having been convicted by a court of an offence punishable under this Act, commits the same offence shall, for every such subsequent offence, be punishable with imprisonment for a term which may extend to two years and with fine of five thousand rupees:

Provided that where such subsequent offence is for failure by the employer to pay any contribution which under this Act he is liable to pay, he shall, for every such subsequent offence, be punishable with imprisonment for a term which may extend to 3five years but which shall not be less than two years and shall also be liable to fine of twenty five thousand rupees.