How do I update jailbroken iphone 6, ios 8.1.2 to ios 9.3.3?

My iPhone 6 has been jailbroken for some time. It is presently running on ios 8.1.2 and I would like to update to ios 9.3.3. I understand the latest ios 9.3.4 will not work. How can I achieve this? And is it possible to find a program that will save all my stuff and cydia apps when doing so?
I would very much appreciate any advice.
Thanks.