The plants will produce more liquid when new insects enter the traps. They release enzymes. Also, it's better to repot these early in the season BEFORE they start putting out pitchers. When they start waking up in the case of Sarrs.

Tom

Well, I know it is troubling to spill all your Nepenthes fluid out, but it wont hurt the plant if it is adapted to you home or wherever you grow it. Just give it a couple weeks (usually less) and you should see it produce its own fluid to replenish what was spilled. You can repot Nepenthes any time of year as they are tropicals. They should produce pitchers year round if they are getting adequate light. In any case, if you dont mind loosing a pot, you could just cut up the old pot with some shears to get the plant out carefully without spilling its fluid and carefully remove the old soil and wash the roots with distilled water before repotting, just dont let the plant fall over or it will spill anyways.

I repotted my sanguinea about 4-5 months ago and all of its fluid spilled out on my hands. It happens, its a dirty task. You just gotta do it and get it over with so the plant can get back to adapting to the new pot and regrowing. My sanguinea replenished its fluid in a few days and kept on digesting the insects it had caught.