Hi dranomax,
transplanting most carnivorous plants is easy, but not sundews.
Squeeze the pot, then turn it upside down and sort of pull the plant and sqeeze
the pot at the same time.The soil should come out looking like it was molded by
the pot.Then gently tease the soil away from the roots or wash it off with a bowl
of distilled water.Try to get as little soil on the leaves, bieng very carefull to not
damage the roots.
Good luck,
Adrian

If the top of your terrarium is narrower than it is at the soil level you will have to dig it out. As carnivorousplants notes above, the root system can be quite extensive so dig out a generous clump of soil.
-Don

Never pull a plant up, at least not unless you want to try to kill it. Use your fingers and scrape away some soil several inches from the plant's base on all sides and stop when you feel a root, dig down along the root until the root comes up easily and continue until you have the entire root mass dug up. Some snapped roots are not going to harm the plant and will likely grow new plantlets if they are repotted about 1/8 inch in sundew mix. Once you have the plant loosened, just cradle it in your hands to keep the leaves from picking up too much dirt (this will happen anyways, but it will not harm the plant, just give the leaves a good spray after transplanting it). Use a tray of distilled water about an inch or two deep to soak the root mass in to remove old soil, then repot it in a big enough pot that will handle the entire root mass. Do not pack the new soil too firmly around the plant, just tamp it down lightly and leave it a little loose and spongy, then water the plant well to firm up the soil around the roots (make sure the moss is moist before potting the plant in it).