Yes kids do slow down their eating at this age, but they don't normally stop eating. I can understand your frustration. If she is drinking too much juice or anything for that matter, that is probably filling her up. If it were me, when she asks for a drink, I would tell her she had to eat something first, especially at meal times. You can check with your pediatrician to see how much fluid she needs during the day.
Offer up a handful of cereal or something small then when she eats that, give her a small amount to drink. This may feel mean at first, but 2.5 year olds want control. Some control like choices of something to eat are ok, but total control is not.
Hang in there. Most kids will eat when they are hungry, It just seems like she is filling up on liquid.