Hey Exeonx!
Basically, it is not necessary for you to make a fresh install of your OS (although it's recommended). You could just clone your older SSD onto the new one and set the new SSD as the first booting option from your BIOS/UEFI. As usual, you should backup any important data which you might have on your old SSD, just to be on the safe side, in case something unexpected happens. Afterwards if you plan on keeping the old SSD as a secondary storage drive, just reformat it, so that you are sure that there are no residual system files left on it from the OS, but do this only after you're 100% sure that you can properly boot to Windows with your new SSD.
About migrating your OS to a new drive, you could check out this tutorial: http://lifehacker.com/5837543/how-to-migrate-to-a-solid-state-drive-without-reinstalling-windows. I know it's about migrating from an HDD to an SSD, but the process is basically the same. It's even a bit easier as your new drive would be larger than your old one and you don't need to slim down the old SSD.
Hope that helps. Please let me know how everything goes.
Boogieman_WD