How you get your access to the internet makes no real different for updates. If there is an update, you would see it in the "Settings" on the device. If one isn't listed there or doesn't show there, then there isn't one for that device.
The only way, then, that you could use a newer OS would be to root the device. I am not an advocate of that as it is very risky. You can try asking about doing this in the "Rooting, Jailbreaking & Unlocking" Forum. http/www.tomsguide.com/forum/forum-117.html Yes, it is for phones, but they should be able to help with tablets as well.