Try a compost tea.

Some thatch, about 1/2 inch, is good for a good healthy lawn. If more than that builds up then you need to look at your management practices, what are you doing that is preventing the Soil food Web from keeping the excess thatch under control.
Spraying molasses might, in the short term, cause that Soil food Web to diligently get to work but is not a long term cure for any problem. Getting adequate levels of organic matter into the soil is what is needed.