It doesn't hurt for your beardie to eat its old salad however it has fewer nutrients in it because of how long it is in the heat. Just to let you know your bearded dragons
UVB light should turn on at 7am and off at 7pm because it is Autumn and this is the most natural schedule for them. Since she is not eating check that: she is happy in her home, the UV is right, temperatures are right, humidity is right and they aren’t shedding. If all of this ok, it could be that she has an infection or has been overloaded with parasites. Since you said she looks old she is most likely to be dehydrated as wrinkled skin shows that. This will help your bearded dragon as it is dehydrated and not eating enough. Method:
Stir reptile electrolytes or Pedialyte into a tablespoon of strained baby food (chicken or beef flavour). It should be as thick as pudding. Use an eye dropper or oral syringe to put a bit onto your her lips, being careful not to get it in their nostrils. Hopefully he will lick it and repeat it if necessary. Maybe you can try using different vegetables or greens or herbs to interest your bearded dragon more.