Fermentation is complete. Mid-60s for attenuation is as high as the Irish ale yeast can get.
I think you could add a pound of sugar or brown sugar if you like to bring effective OG up. But it won't change the FG, it will still end at about 1.020 plus or minus one point. I would dissolve the sugar in 2 cups water, bring to a boil, cool, and add to your fermenter. Then give another week for it to ferment out. This should get you closer to what you wanted.