How can I update my jailbroken iphone 4 from 4.1 to the latest version of

[MaDlHauseR]

os without any saved files? I've gotten along fine until now with 4.1 but its gotten to the point where basically every app I try to dl requires at least version 5. So I would like to update it but am unsure how. I know you're supposed to have some sort of special backup file you make before you jailbreak it but that was all lost in a hard drive crash a long time ago. So I need your help to let me know exactly what I should do or where I can find what to do in order to update with out putting my phone into limbo. I would like to save my apps and other information if possible but it really doesn't matter, I've saved the photos and backed up my contacts with google and thats all that really matters.