I know this is a topic that was on for many times.
But today I went to visit a nursery (A very big one ) that has some hybrid Nepenthes with all the other plants that grow and sell there.
As for that when they water the plants they use fertilizer and can't wash the pipes before they water the Nepenthes and the plant get fertilizer as all the Orchids at the same part.
Another thing they use a plate under the pots so they stand at water all the time (with grow of minerals amount at the pots).
The plants - (N. coccinea and Holland Hybrid) became huge the leaves are about 50 cm. long plants about 100 cm dim. and over also over a meter high.
Of course they haven't got any pitchers but I know if I let rain water wash the soil in the pot in few weeks or so they start to grow huge pitchers .
to make this an good end story the owner want to get reed of them so I got lot of then for a funny price and not long I could have lot of cuttings too.