I'm relatively new to growing Nepenthes and I grow all of mine in 20 gallon long terrariums. Each pot sits in its own shallow water saucer. The way I've been watering is as follows:
I'll top-water the plant until water completely fills the saucer. I then let the plant sit in this shallow water until it evaporates (usually takes roughly 4 days - sometimes longer). After that, I'll let the plant sit with no water in the saucer for another 3-4 days, the soil remaining quite moist. When the top of the soil becomes somewhat dry, I repeat the whole process again.
My Neps did ok with this method, but still aren't thriving. I'm now only watering until a small bit of water appears in the tray, then letting that evaporate until I water again. This the way the plants aren't sitting all the way in the water (a Nepenthes sin, I know!).
I haven't been able to find a great way to water my Neps without taking them out of the terrarium, letting all the water drain away, and replacing them again. I want to keep them all situated in the tanks!
It's been a frustrating journey, but I've learned a lot and am still learning. I hope my Neps will do a bit better with this slight tweak in my watering ways.
Can you all please post and share how you water your Nepenthes? I'm especially interested in the methods of those who keep their plants in tanks. Thanks!