Is the vents stuck with dust?

brought mine, cooler master x-lite @rm49 with card reader FOC

my tip..

try putting 4 matchboxes on each edge(of course do not put the matches,replace it something else). pretty much it improves ventilation and can reduce temperature by 4-5 degrees

Dust cleaning is advisable~
Reapplying thermal paste is only required when temperature rises above normal range.. [You can check your temperatures using HWmonitor if haven't already  ]

Opened up the laptop and clean?
Or can opt to use vacuum cleaner or compressed air as well~

CM Notepal U3 

You need to download the step-by-step teardown specifically for the A42Jv; shouldn't be too hard to find considering that the A42 was quite a hit some time ago

You can apply on both the CPU and GPU
Remove the existing thermal paste (or residues of it) using alcohol, then reapply thermal paste by spreading a bit onto the metal plate (noneed to spread), just close it up... the pressue and the heat will do the rest~

Yea, last I checked All IT does sell Cooler Master thermal paste

That one doesn't seem like a step-by-step guide
If you're not sure about what you're doing, better ask for help rather than taking the risk of doing it yourself? 

+1, its hard to say whether your thermal paste has degraded or not... the only way to notice are through the temps...
You should clean the fans though, most of the time its really clogged up after 1 year

Not sure how to do it on your laptop, but you need to first access the fan, there should be quite a lot of dust clogging the metal exhaust, remove them...
as for the dust on the fan blades, you can try removing them using a vacuum cleaner or compressed air

Cleaning the fan blades won't help if the exhaust is completely clogged and blocked by dust (just like in mine  )