Reviving yeast for carbonation

So I am making a cider with the White Labs WLP-665 Flemish Ale blend. It uses Brett so fermentation has taken a long time. (4 months!)

The problem is, it took so long that I stashed it in a closet and haven't checked on it in a couple weeks. The airlock is no longer bubbling, so it's pretty safe to assume that fermentation has stopped and it's probably time to bottle. Unfortunately, fermentation stopped somewhere between 1 day and 2 weeks ago, and if it was on the long end of that timeframe, the yeast is probably quite dead by now. I am not a fan of flat cider and I definitely want to carbonate, so what do I do to revive the yeast?

I have a few packets of Red Star champagne yeast that I use for my everyday session ciders that I could add to the mix, but I don't know if that will affect the flavors that I have waited so long to develop, not to mention that I have no idea how much to use.

If I add a little corn sugar or apple juice, could I wake up enough yeast to carbonate, or will I have to add extra cells? Any suggestions?

If it's only been 2 weeks, then your yeast probably isn't dead. Rather, it'll have entered a state of slowed activity that closely relates to hibernation on the cellular level. Once you hit 3+ months, or have filtered, then it may be a good idea to add more yeast at bottling time. More sugar should wake those little guys right up.