I think it is time for a thorough clean. If you aren't confident yourself, then get a local specialist to remove the bumfluff. It will be much cheaper in the long run. A major cause of this problem, is by setting the laptop upon one's lap. The sh1te, gets drawn up so easily. At home, there are solutions to the prob like a laptop riser. This is a USB powered and angled rest, which will blow air into it and keep it cooler than before. They are cheap, too.
Conan