WD Green Transfer rate drop

So my HDD after third year of usage start to drop transfer rate hugely. Is there anything that i can do beside buying new disk and reinstall OS? The other disk (which run other OS) don’t have the Parkinson.
Windows 7 64bit
HDD: WD Green 1TB WD10EARX 64MB cache SATA-III

Hi,

Make sure to test the drive with the WD Dlg tool to see if you can identify any specific issue with the drive.

As a recommendation, try defragmenting the drive, that might help with the performance of the unit.

See if the following link helps:
http://windows.microsoft.com/en-us/windows/improve-performance-defragmenting-hard-disk