Are you using rain water or distilled water? Tap water is not good for this plant. Also, does it get enough sunlight? It can handle (requires actually) direct sunlight. Reason I ask, is because the tentacles on the older leaves are red (because of the sunlight), but the newer ones seem to be lighter. Testing the mucus may give some indication too. If you touched it when you bought it, you may remember it to be thick and sticky. Low light may cause it to become more runny.

@Stephie It generally can handle it, although it's safer to be a little less generous with water for indoor plants in small pots. I'd recommend giving them about 1/4" (0.5cm) in the dish, and not replenish that until it's mostly gone.