Maybe try getting the freebies in the paper over the weekend, or the SW magazine, it might have something new in to inspire you, wether its a story or a recipe. Maybe switch which plan you follow? or give yourself an incentive.
I stray every now and again and I find it helps to put on some of my clothes from when I first joined and REALLY see the difference, I think sometimes you forget how amazing you have done. I also have written on the back of my book the reasons I joined. Reading through these and really thinking about it, and thinking how differently I feel now is a little kick up the butt.
Failing that I text my consultant, who is THE best, totally honest and frank about his own relationship with food and what he thinks of your situation (if he thinks youre having an off week or just a whinge he will tell you to suck it up haha) but if you genuinely need help or a change hes there.