Are you overclocking your CPU ? What are you using for thermal compound ? Some compounds can take up to 6 months to cure and start providing better (lower) temps, it depends on how much time the computer is actually on.
When applying thermal compound it should be applied in a very thin layer since the objective of the compound is to fill any microscopic or very small grooves and pits so that there are no air pockets. In this case more is not better.
You can change the thermal compound any time you want , but you want to make sure that you have cleaned out any dust build up on the heat sink fins or the fans blades as that will also cause temps to fluctuate. You also want to have good air flow through your case so a good number of fans (3 or4) should be in the case.
I use Artic Silver 5 so you can see if they sell that on Ebay.in which they should because it's a very popular thermal compound however it does take a long time to cure but it will last that much longer.
Currently I have it on my computer and it was applied 1 year ago to an i7-3930k overclocked to 4.6ghz with very acceptable temps even after 1 year. Low to mid 40c's at idle and up to low 60c's at full gaming.