There are one or two ways you can upgrade the Bluetooth revision supported by your computer.
The really easy option
Our first suggestion is to simply purchase a USB Bluetooth Adapter that complies with the latest standards. If you do this you may also want to follow our guide on how to disable your existing adapter. This means that you won't have to open your PC or pay someone else to do so.
I want to replace the actual Bluetooth hardware inside my computer
There is a good chance that the existing Bluetooth hardware inside your computer can be upgraded with a new internal Bluetooth adapter card. If you've never taken a screwdriver to a computer before now is probably not the best time to try so you will want to talk to your retailer or a 3rd party repair service about such a possibility.
If you know what you are doing and are not going to invalidate any warranty your computer has by opening it then you will need to first determine what PCI bus standard your Bluetooth card uses. That is vital to know before you try to purchase a replacement card. Also be aware that your Bluetooth card may also contain a WiFi chipset to let your desktop connect to wireless networks. If so make sure your replacement card is a similar combo card.
REMEMBER that you need to know exactly what card type is required in your desktop computer. Some desktop cards use different slot types (i.e. PCI, PCI-e x1, x16 etc). Replacing your Bluetooth adapter is done at your own risk! If you are at all unsure about this procedure it's best to consult a PC repair center.