Hello Jack! Welcome to the forums. I see you joined in December, but have not posted until now, glad you decided to.
I know your weather is quite a bit different from ours, but it sounds like your Nepenthes may not be getting enough humidity. A Nepenthes will grow well, produce new leaves and may even start to vine, but without the proper humidity will not produce pitchers. Do pitchers at least start to form? Is it growing in the same place it was last year or at least comparable conditions? My alata started putting out pitchers in February, when the temps we more steady in the 70's and humidity was only about 65%. What conditions (temp/humidity) is the Nepenthes in now?
I finally got a reader and the temp is sitting nicely at 20 C (70s) and humidity is 65%+, so I'm guessing it must not be getting enough direct sunlight to produce pitchers?