Can't update Whatsapp!

[Fabiola Espinoza]

Hi!
So here is my problem: I just moved to a new country, so I changed number. I wanted to update my new number in Whatsapp, but it said that my version of whatsapp was too old. My iPhone is jailbroken and it is iOs 4.2.1. I tried updating whatsapp on Cydia but I couldn't. Then I tried on iTunes and it said that I need iOs 4.3 to do so. So I think that's the problem.
How can I update to iOs 4.3 without losing any information? What I really wouldn't like to lose are my contacts and my conversations on whatsapp.
Thanks!

 

[Massie]

The easiest way would be to just do it in iTunes, but that would mean losing (and redoing, if possible) your jailbreak. If you need to save that it gets more complicated. What kind of device is it? And do you know if you have shsh blobs saved?