Kelly,
I always tend to err on the side of completing all phonics instruction to make sure kiddos have been exposed to all the rules. During the first part of my public school teaching days, whole language was in vogue, and kiddos often had phonics gaps that didn't show up until third grade when chapter book reading came into the picture (and the children's word banks were full). With full-blown chapter books, there is no guessing your way through the rules for pronouncing words.
With each of my own kiddos, we found they were reading very well 2/3 of the way through their phonics programs, but I was often surprised as I finished the program that there were a few rules they didn't know (and would have missed out on had I not finished).
You may wish to set the timer for her phonics lessons and have her go as far as possible in 'x' number of minutes. Often if kiddos know there is a definite end time, they are more likely to work hard during the whole time. Let her know as soon as she's finished the book she's done with phonics!
You could also begin the Emerging Reader's Set while finishing phonics if that is motivating to her.
Blessings,
Carrie