Hi jotebo,
First, nepenthes are relativley tolerant of tap water, so don't worry about it.
You should clip the pitchers off when they're completley dried up so the plant
can get the most photosynthesis out of them.Once the pitchers start to die
they won't come back.Carnivorous plants don't need insects, they just help
it grow faster.If you want to feed it then spray it with some weak fertilizer.

Good Luck,
Adrian

I would start with this website:

http://www.sarracenia.com/faq.html

If you do fertilize, use a diluted orchid fertilizer to fill the pitchers halfway. You can also use diluted neptunes harvest for the roots, but I wouldn't necessarily recommend this to a beginner. To keep pitchers alive longer, fill the empty pitchers with distilled water. Normally they inflate with a thick enzyme filled fluid that helps break down bugs, but if this is gone, you can use the weak orchid fertilizer or distilled H20.

Most importantly though... read read and read some more. This will also allow you to find your answers without waiting for someone to answer them for you.'

Oh yeah... what makes you say the plant needs to be repotted? Is it in a very small pot, or is there another reason?