I had the same trouble with earthworms a couple of years ago. They
were quite literaly burrying my pygmy sundew with the growing
medium they were pushing out on the surface of the pot.
To save the plant, I did the following. I put the pot in a bowl and
added water into it until the waterline became even with the soil
surface. Once the growing medium becomes fully saturated with water--
sort of a slury, the earthworms poke they're heads up for air. At
this point you are standing on the ready with a pair of tweezers. Grab
the worm and pull it out of the pot. Dispose of it. That's all there
is to it. This does take time, however. The worms don't all come up
at once. If they get the slightest inclining that the tweezers are
coming for them, they dart back into their water-logged hole. They
have surprisingly good reflexes.
I cured my pygmy sundew of the earthworm menous with just one treatment
of the above method. You'ld be surprised how many earthworms can fit
in one pot. Anyway, bare in mind that such a high waterline isn't
good for your CP typically. Don't leave it in this waterlogged state
for longer than is absolutely necessary!
Good luck,
--Zachary--
P.S. I have only needed to do this once. If for some reason your plant
dies, please don't blame me. This is something you do at your
own risk.