My best guess, without looking at the lawn, is that you don't have a thatch problem. If you do (again doubtful) then you have more things to worry about than that. That would likely mean that you aren't doing even a single thing right when it comes to taking care of your lawn...over fertilization (especially with synthetic fertilizers), poor watering habits, improper mowing, etc. etc. etc.
You are approaching a good time for Fall fertilization, hopefully with an organic based product
Check with your local nursery or feed and seed for some options. Here in the D/FW area even HD and Lowe's have some organic products in stock.