Photo would help
But one thing that you can use is if the traps are closing quite fast when you feed it insect, if it closes fast, it is an indication that it is healthy (but not the only indicator). Big traps, new leaves and traps growing are others. I also tend to think that at least with the types or variety that is known to grow up and not hug the ground, if the leaves start to hug the ground it might be going dormant or not doing well.
TTFN
Arvin