unless there is a formal upgrade, I would not upgrade, could basically turn your tablet into a brick. since you did not give the full model number, there is no way to help since any updates is model specific. You may also want to check with the xda forums since they are the experts and would know if there are any android versions available for your specific model.
I have a Lenovo Think Pad tablet that runs android 4.0.3 and I need to update to a newer version. Lenovo does not support this anymore. It's rooted but I can seem to find how to update. Thanks for any help. Please remember this a tablet, not a laptop.