Just test again in 20-30 minutes and if she's coming up, test again in an hour to make sure she stays up (without having to feed her more)
Don't feed her too much....you don't want her to fill up in case you need her to eat more later. Usually a couple of teaspoons of just the gravy part is enough.
What we do is pop the top, put it back down and "squeeze" the gravy into another bowl (that's where the carbs are anyway...the gravy )
You can get quite a bit of gravy out of one can if you squeeze hard! (messy, but it works!)