You're not wrong, this is the normal life cycle of leaves on
Nepenthes. A good number of Neps can take a couple YEARS to
become established. At which point, they become huge monsters
and need pots at least a foot wide. It sounds like your plant
has one vine and one growth point thus far, correct? After
some time, it will grow new vines from around it's base which
will be stronger than this first vine. The leaves will be larger,
last longer, ect. One thing though, are all the leaves on the
plant pale, or were you refering to the older dying leaves? If
they all look pale, then you should try a 1/2 strength application
of fertilizer. Don't use much of it on the soil but spray onto
the leaves and in the dying (will not help they're completely dead
though) pitchers for the most part. After 10-15 minutes mist
the plant with water only, to the wash some excess fertilize off.
Dave Evans