Okay, you are safe to repot. You will need a slightly bigger pot, if you have a 3" pot, repot in a 4" pot, etc. You will need medium bark mix. Do not use the old bark. First take the chid out of the original pot, and rinse any bark off of it, then repot into the new pot. Keep in mind that orchids don't need large pots, they prefer to be tightly fitted. If there is too much space, then the medium will retain moisture, which is bad for the plant. Dendrobium orchids in pretectular like very small pots, so you may not need to do so.
I hope this helps! Maybe post some pictures so I can see how it looks, and I can tell you whether or not you should repot.