Certified GKH Gardening Expert
Actually, that mixture is just fine! The best will be Sphagnum and perlite, at around 30 percent perlite. (Some people split 50/50 which is fine, too.)
These will take quite awhile to root, so it will be necessary to do these in an area where the humidity can be kept very high.
This article will help you to propagate Nepenthes: https://www.gardeningknowhow.com/houseplants/pitcher-plants/rooting-pitcher-plant-cuttings.htm