Pitchers do not last forever. Cut off the ones that are looking bad to you at the tip of the leaf. What gardening zone are you in? Give it bright, indirect Sun and keep moist at all times with distilled water or rainwater. You do not need to feed the pitchers either.

I've had an N. alata for five or six years and its pitchers do much the same. It winters in the greenhouse and spends summers outdoors; it bloomed last year. It's growing like a weed - vining like crazy, lush and healthy as can be - but a lot of the pitchers get 'crispy' at the top while still having fluid in the bottom. I've done autopsies on dead pitchers and they seem to be eating very well, so I was wondering if maybe this is the plant's response to having a full belly. "Hey, I'm full < burp> can't eat any more...." so there's no need to attract any more food.

Nepenthes can do that when stressed from a change of location. Pitchers also die in that way: the top dies first but the plant keeps the bottom part for some time to absorb the rest of the liquid.

Your plant is probably a hybrid of nepenthes ventricosa x nepenthes alata. That cross is called nepenthes x ventrata.