Restore iphone without updating
Before we get into backing everything up, you'll need to make sure you're connected to a Wi-Fi network, otherwise you won't be able to back up your i Phone.
This is probably why most people don’t bother jailbreaking, but that’s a whole other article!
Jailbroken i OS firmware can run riot accessing different parts of the filesystem usually only reserved for apps and system components.
If a tweak you were using has been storing data in an unorthodox place, and you create a backup of this data, when you restore the phone you might never be able to access (or delete) said data again.
Upgrading to a new version of the i OS used to mean that you had to be in front of your computer, had to connect your i OS device to it, download the update to your computer and then install the update via syncing with i Tunes.
But ever since i OS 5, that's not true anymore.