New apartment rentals in Manhattan more than tripled in the third quarter, as landlords offered fewer concessions and tenants sought better deals by moving out. New leases signed surged to 8,593 from 2,549 a year earlier. A year ago, landlords were offering deal sweeteners such as two or three months of free rent, gift cards and payment of broker fees. Tenants are now seeing increases on their lease renewal and no free rent.