only thing i would touch would be tires and/or tubes. Rig is a budget bike as you know........not worth upgrading in my opinion as it defeats the purpose of the budget price point. I would sell it and start over if I really wanted to get a lighter bike as that would be cheaper IMHO in even the medium term.
Would also consider selling the Reba and picking up a Pace, Bontrager, On-One, or White Brothers carbon fork as after selling the Reba, it would not cost much, if anything. For your riding, up to XC riding or even some AM riding thrown in, a Reba is definitely not needed.