Trying to clean an old spill is one of the hardest things as what was spilled could have had the time to corrode things to the point it can't be fixed without replacing parts.
Juice is one of the hardest things to clean out as you have two things within it that damages things: Acids & Sugar.
Both require Water (distilled) to dilute and carry off not alcohol. You still need a good grade of Isopropyl alcohol (85% or better) to then clean things again to remove the water (acting as a dryer).
OK so what to do?
First I would think about just replacing the top case assembly as it will give you a new keyboard in the process. It will be the easiest way to fix your problem.
OK, you want to try to fix the keyboard.
You will need to completely remove just about everything to get the top case off to even get to the keyboard. Once you get it out you'll have over 50 screws or rivets to remove to take the keyboard apart. Carefully take the pieces off and clean them in distilled water. Inspect the pads and the PCB surfaces for pitting or any staining. Again, use distilled water to clean as best as you can. If you see any damage you'll need to replace the top case as you can't get the parts alone.
Last option here is to use a bluetooth keyboard and mouse or trackpad.