Two things I did differently this year- I kept them in my sunniest window away from the humidity, and I watered sparingly, just enough to moisten the soil and letting the soil dry out between watering.
They continued to grow and bloom throughout the winter. The plants were now quite lanky and in need of pruning.
Here's what I did:
1) Removed dead or dying leaves and all blossoms
2) Cut a few inches the tops off each stem
4) Dipped stem in rooting powder
If what I've been learning holds true, I hope to have some new geraniums this year.