IPhone 4 software update to ios 6?

I have an iPhone 4 on iOS 5.1.1. I want to update my phone to ios 6.0.1
My prob is that I hav installed cracked apps on my phone using jailbreak ( installous) And I'm afraid that i will loose all my apps and the data if I update my phone.
Please tell me how to save the apps and safely update my phone to ios 6.
Thanks.

Added (1). What if I want to restore it iOS 5.1.1 only?
Can I backup my apps on pc and reinstall them after restore or update?

Yes you will loose it all after you update and you have to jailbreak and install those apps again. As far as i know there's no jailbreak available for iOS 6.0.1 so stick with iOS 5.1.1