This is your niece and therefore, technically, you're a guest at the wedding as well. You should charge her for the wedding, but only to cover the expenses of printing (assuming you're using digital exclusively). Think of it as your wedding gift to her. You wont come out ahead financially in the end, but it's not like you're missing out on a higher-paying job. If you weren't the wedding photographer you'd probably be there as a guest anyway. Besides, think of all the free food and champagne!

