Kat,
Remember...if you offer her a meal every week, you are spending the same amount on rodents whether she eats them or not.
I know...I hate to throw them away, too (one of the many advantages of having several snakes...there's always someone willing to eat the leftovers).
If she is eating every two weeks, but you are only feeding her on Saturday (therefore making her go two weeks if she refuses a meal), have you considered going to every 9 or 10 days for awhile and seeing how that goes?
If she is generally healthy, going two weeks between feedings for several feedings in a row will not harm her. If you don't want to get out of your weekend feeding routine, feed her every 2 weeks for a few feedings, and then offer her a meal after a week eventually. I still think 9 or 10 days between feedings might be the answer for now.
As the days grow shorter, she may very well go for longer periods between meals, especially if your home gets cooler with the coming fall. As long as she eats every couple of weeks, she'll make it through the winter. Don't be surprised if she goes for 3 or even 4 weeks between meals at some point before the spring. Good luck. Duffy