Are you providing water, either in the form of a small bowl or by regular soaking? If not she might be dehydrated. If you suspect dehydration, try soaking her in shallow water for about 20 minutes.
Has she been defecating regularly? Does it appear normal or is it loose, runny, smelly, etc? If loose, smelly, etc. it could be parasites. This requires a trip to the vet.
Do the lights turn off at night and the temperature drops a little? My leopards tolerate lows in the 65-70 range very well, and I wouldn't want to keep them at 85-100 all of the time. Excess heat can lead to dehydration and other problems. Temps too low at night could cause physical stress.
Does she get a diet with plenty of fiber and calcium, no meat products, etc? A bad diet can lead to illness and reduced activity.
If this has been going on awhile, a trip to the vet with a fresh fecal sample would be a good idea.