This is doing incredibly well putting on lots of new leaves with tiny buds of the pitchers on them

Something very low in nutrients. In the wild they grow in inhospitable places and have evolved the pitchers to supplement their diet by catching insects.
My 'bible' recommends a mix of 2 parts bark, 2 parts perlite and one part coarse peat or coconut fibre.

Thanks Andrew..I will have to go shopping for more perlite. Cheers!

I would also use ericacous compost too.

Yes, a jungle plant, so leaf compost ideas from bark and peat and coconut fibre will give the ericaceous needed, with perlite for extra drainage and moisture retention!