In theory you could, and this should bring this back up to full gloss but there is a potential of it not being completely smooth. I would suggest coating a small area, like a cut off first before moving onto the main project and see what the outcome would look like.

I am sorry i do not have better news for you.

Good Afternoon,

You could apply a brush coat of GlassCast 3 over the top of this however, this will then be too thin of an application for the resin to self level and you may find that you get very tiny witness marks in the surface. Not sure if you have already, but it may be worth watching our resin river table tutorial as near the end of the tutorial, we simply add some danish oil to the wood and polish the resin using the NW1 polishing compound. 

If you have any further questions, please do not hesitate to ask.