My N. alata "highland spotted", which I've had for ~3 years now, is no longer pitchering. It is growing well and looks healthy otherwise. When a new leaf grows, the tendril ends, instead of flipping up in the usual way, curve backwards toward the leaf. Sorry, no pics, but here's a drawing that might help:
I first noticed the problem ~9 months ago(?) The plant started to slow its pitchering, producing pitchers every other leaf, then every third one, and so on, until it stopped altogether. I've tried everything I can think of, from raising humidity levels, changing watering frequency, to changing the growing medium. Even tried superthrive. Nothing has helped. The plant has always been in good lighting.