They sure do grow back .. no need to worry about it ... the only thing is that they might or might not have an appitite issue while it's growing back ... One of my TSN's has lost each of the long whiskers and each time he refused to eat for a good week after they started to grow back (looks like a little thin string at the end of the old whisker)
you may want to try and get ahold of it and clip it...it should help it grow back healthier...but to reiterate what everyone else has already said yes it will grow back