My girlfriend has sort of strong perversion for colored stripes. She likes stripes on everything.
So I decided I could set up a little surprise for Christmas and I made I program that generates pretty colored stripes and sets them as windows desktop immediately.

I now need to make sure this program will eventually start generating the backgrounds for her after Christmas (24.12 this year - 2014). However I can't get to her computer without her knowing very often so I need to set up something automated.
Best solution is the one that can be easily disabled without my assistance (eg. if she tells me she doesn't like it anymore)
What can I do?