In case the corporate authorities of any city have attempted to levy any assessments or taxes for improvements, or for the payment of any bonds or other evidence of debt, which assessments, taxes or bonds are or may have been informal, illegal or void, for the want of sufficient authority or other cause, the council of such city, at or before the time fixed for levying general taxes, may relevy and reassess any such assessments or taxes in the manner provided in this act.