I've been at clubs where smokers have to re-pay entry fee every time they go outside for a smoke. It seems reasonable as clubs often are operating a one-in one-out policy due to numbers, so if someone has gone out for a fag, they can let someone else in and in the meantime someone else might have actually gone home so smoker can then return. The club do not have to let you go outside to smoke (and come back for free), it is not a necessity.
Although the doorman may well be making a quick buck!