Eyelashes are the same as all the other hair on your body. They continually fall out and are replaced.
Unless of course you have alopecia.
Curious though as to why you would want to pull them out?
i haven't pulled them out deliberately! mine just seem very weak, and if i have mascara on them, and am taking it off, eyelashes seem to come off too. only a couple mind! thanks guys! glad i'll get them back