When you update your iPhone or iPod, you loose all of your data, You can backup all of your data which iTunes automatically creates fro you when you sync your iDevice with iTunes. But I recommend you to use your updated and jailbroken iPhone or iPod as new to have faster device, less battery drainage and many other benefits. But in this way you will loose your important data all messages, contacts, notes and calenders. So I'll tell you how to manually backup your contacts, calenders, notes, messages etc.

Download this utility DiskAid.

Connect your iDevice with PC.

Launch DiskAid. Select Root Folder as shown in this picture.

Now to back up your data do the following. 

For Contacts:

• Navigate to /private/var/mobile/Library/AddressBook
• Save both files (AddressBook.sqlitedb and AddressBookImages.sqlitedb)

To save a file on your computer, right click on that file and click on Copy to PC, then select where you want to save.

For Messages:

• Navigate to /private/var/mobile/Library/SMS
• Save sms.db on you computer

For Notes:

• Navigate to /private/var/mobile/Library/Notes
• Save notes.db on your computer

For Calendar:

• Navigate to /private/var/mobile/Library/Calendar
• Save Calendar.db on your computer

For Call History:

• Navigate to /private/var/mobile/Library/CallHistory
• Save call_history.db to your computer

When you want to restore your data after updating and jailbraking, navigate to respective folders and replace those files you already saved earlier. To copy files on your iPhone Launch DiskAid and select the target directory then click on Copy Files to Device and select file you want to copy.

Now check your iPhone or iPod, yeah, you have manually back up your data.