I would look into getting a core aeration done. Now would be a good time to do it, and then put down a good (slow release) winterizer formula fert. Something like a 9-30-15. If it is slow release, the N will not be available until the spring of next year and will then give your lawn a good kick start in the spring. The low N will help make sure that the turf is fed properly, but not too much, before the fall.
I would go to a reputable garden centre to get the fert (ie, not Home Depot, Walmart, etc).