Cutting the plants back will often cause little growths from the woody looking parts of the plant. Radical cutting back is a last resort, but one I get to more often than I'd like.
Notice how the stem where the growth is occurring is close to the medium? I don't think that's a coincidence. One way to propagate neps is to scrape or lightly slit a stem that is drooping down over the medium and push the stem into the medium where you cut it. That's supposed to make a new plant. I think that's what you are seeing.
Neps will make basal growth periodically, new vines from the seemingly "dead" parts of the stem, reproduce from a vine growing down in the medium, or reproduce sexually if they feel like it, I guess. Cutting plants back always stimulates new growth, if the plant isn't sick or dying. Any accidental damage to the plant can cause new growth. I'm still working on how to benefit from that one.
I just, um, made a minor temperature error with a couple ampullaria that were pretty well rooted. I cut the plants totally back into the "wooden" part of the stem -- removing all the leaves (they were dead or dying). That's radical surgery, I know. I'm already getting little growths on the red ampullaria (Thank goodness) to replace the upper part that I, honestly, accidentally refrigerated outdoors while on vacation. The green speckled ampullaria really didn't like the wind chill to say the least. It was covered, but not enough. I'm in wait-and-see mode.
Making emergency cuttings from dead -- looking -- vines is not the end of the world. If you kill the leaves and pitchers, as bad as that is, it does not mean your plant is necessarily dead. As you can see, the older parts of the plant will kick out new plants or new vines.