I have had a couple instances when a plant did not regrow from the bottom section after removing the top. These were plants that had numerous healthy green leaves remaining on the lower portion too. Usually it is not an issue though if there are some healthy leaves left on the bottom piece.
Turner - usually you want to have at least a few inches of stem on the cut piece. For many young Nepenthes this means a long time of waiting (years in some cases) before the plant gets tall enough. Some plants will get taller faster so how long it will take to 'mature' is highly variable on the type and how well it is grown. Some plants even when mature and vining will vine faster than others with lots of stem inbetween each leaf.