Well RamPuppy lets start in the other direction, what kind of light source are you using. N. bicalcarata's leaves should last a good amount of time though not as long at a younger age. If all the other conditions appear to be right then the problem is likely with to be strong light. When I first got N. bicalcarata the leaves died very quicky untill I moved it under my shade choth with N. hirsuta and now its leaves have lasted a good bit longer. A good way to tell is if the leaves start to get brown patches in the middle of the leaf (not going brown from one end moving to the other which is natural) and then the whole leaf dies later. Burning is a problem with the species I mentioned above. Their is one other species I found that doesn't like strong light and that is N. macfarlanei. Oh Rampuppy, my desciption of strong light is if all your other Neps love it(grows fast and sturdily with good colouration) and the species I mention hate it then it is strong light. Lots of Luck.