(b) if the breach is capable of remedy, requiring the lessee to remedy the breach; and the lessee fails, within a reasonable time from the date of the service of the notice, to remedy the breach, if it is capable of remedy. Nothing in this section shall apply to an express condition against the assigning, under- letting, parting with the possession, or disposing, of the property leased, or to an express condition relating to forfeiture in case of non- payment of rent.]