Look at the exact terms of your lease. Given the limited information, it seems that you are not in the position of having failed to reject the renewal of the lease, but are attempting to break the lease mid term. If so, absent any other controling term, 60 days notice should have been fine. If so, the LL had / has the burden of mitigating his damages within the notice period. If he fails to do so, you are relieved of your burden. The court will look at the facts to determine what was reasonable. For example why do you want to leave?