Christmas beer FG to high. What to do?

I was not sure in what section to put this.

The thing is that we just started using a new electric set-up and it looks like the temp sensor/controller (PID) is a bit off. Looks like we mashed too high.

Our so called Xmas beer fermented from OG 1.065 down to only 1.019
It is just a plain ale, no spice nor anything fancy. Was suppose to be a slightly stronger, slightly darker ale.

What can I do to cut through that little bit of sweetness and/or get the bitterness up to cover it.

One thing is to add just over a pound of dextrose to each fermentation bucket and hope to up the ABV by 1% to lower FG (if that is enough)

and perhaps also to boil some high alpha hops and add to the fermented beer, perhaps with the dextrose.

I could really use a good advice here. I have been away from brewing for almost a year due to a super busy schedule and having to spill the first brew out of a freshly built set-up (15 gal.) would be a major B1t3h. Not to mention having to go through Christmas and the new year without HB.

If you're sure it's just an attenuation/fermentability problem, and not just a stuck fermentation, adding a fully fermentable sugar to up the gravity and lower the apparent mouthfeel is probably the best way to go.

I added 1.26 lbs (575 gr.) of dextrose to each bucket. That is about the amount needed to raise it by 1% ABV

The beer reacted immediately.

We´ll see how it turns out in a few days.

Thank you for your reply.