I would guess the thermal compound is starting to lose efficiency and your heatsinks are dirty. Taking the laptop apart to clean it and reapply thermal compound would be a good choice, just be careful and you won't break anything.
Here's a disassembly video
https://www.youtube.com/watch?v=zWqDjAQgMaYOnce you get the board out, be careful removing the heatsinks. The gpu will have thermal pads that you need to keep intact. Just slowly pull the heatsink away from the board after you remove the screws and use the tip of a flathead screwdriver to help the thermal pad come off the board.
Remove the existing thermal compound by saturating cotton swabs in 91% isopropyl and letting the chemical do the work. When clean the processor die should look like a mirror.
The community uses IC Diamond thermal compound. You will need a small tube to do both the cpu and gpu.
http://www.ebay.com/itm/IC-Diamond-7-Carat-1-5g-Thermal-Compound-Paste-Grease-ICD7-NEW-/330961060105...Since IC Diamond is thick, you will need to apply it differently.
Read this
http://www.innovationcooling.com/application.htmlI always soften up the ICD by getting a small glass of hot water, filling it up about half way and sticking the syringe in the hot water for 3-5 mins to help soften the thermal compound. Just make sure the tip on the syringe is air tight, and make sure you don't fill up the glass so much the water gets into the back of the syringe.
Also once you reattach the heatsinks you should clean them free of dust and debris. Use a old toothbrush and a little compressed air. If the heatsink fin is touching another fin in the middle you can gently bend it back with a flathead screwdriver.
Remember don't use force, if there is something stuck or if you are having problems come back here for advice.
Good luck