I suggest restoring to the newest iOS, not just upgrading!
Restoring will wipe your phone, and restore from backup. Upgrading will upgrade without wiping, that will still work, but will leave half a gigabyte of junk on your phone taking space but doing nothing.
Reason: The "disk" on the iPhone is partitioned into a system and a user part, the OS is on the small system partition, your stuff is on the user partition. When jailbreaking, all the built-in apps are moved from the system partition to the user partition to make space for tweaks needing to reside on the system partition. If you upgrade, all that stuff is reinstalled on the system partition, but is NOT deleted from the user partition. When you then jailbreak, both the old inactive and the new stuff will be on the user partition.
Also, when upgrading there is always the risk that some jailbreak stuff may interfere.
Finally, Absinthe works best if you wipe your phone, jailbreak, and restore from backup anyway.