Brewpastor's Water into Barleywine didn't carbonate

I brewed this in May and was really excited to try it. It is really tasty, but it didn't carbonate. I used dextrose and bottled it. I used less than I normally would since it was going to be in bottles over six months.

Is there any way to carbonate it now, or should I just ring in the new year with a flat (albeit strong) barley wine?

You could get carb tabs from your local HB store and uncap, drop tabs, and recap with brand new caps. That would work just fine. I've done it myself with no problems. Granted I haven't done this with 7 month old beer though. How old were the caps you used and did you use pop top bottles or twist off bottles. What temp did were they sitting at when they were priming. I'd still try the carb tab thing but only do it on like six bottles and give 3 weeks at 70 degrees. If it works then do the rest. If not save the tabs til a later date. It should work though. I was watching a special the other night where they were talking about getting bottles that had sunk years ago and harvesting viable yeast from them. Give the bottles a shake after re-capping them to rouse the yeast.