The whole reason I got Jeff was because he lost his upper two incisors.
They grew back in no time at all! Literally a week-10 days and they were back and we've never had any problems since.
Weigh her daily to make sure she's eating enough. If she's got the other tooth, she shouldn't have too much problem. Jeff lost one initially, but the second one was also snapped, it just hadn't fallen out yet. Jeff managed fine with foods that were long and thin that he could get in his mouth and crunch up with his molars. He managed fine with hay, I chopped his carrots/cucumber etc. into long thin strips, leafy things were fine, pellets were fine, as was hay (although he was rather partial to being hand fed the fluffy bits

)
Watch her when she's eating to make sure she is actually eating and not just mouthing at it. You may need to take her out and feed her away from the others if she's a bit slow eating, so that she gets her fair share. If her weight is dropping then she'll need some food syringed to maintain her weight.
Hopefully it'll be all straight forward and she'll have some new pearly white gnashers in no time! If she's eating ok by herself, and maintaining her body weight then you probably won't need to see a vet. Hopefully it'll just grow back and meet up nicely with the others, but keep an eye on the teeth to make sure they align as they should do, or that will be a trip to a dentist!