I've been doing the Strong Women Stay Young program for a year, and I'm outgrowing my ankle weights! Can I use heavier weights?

Congratulations! But I do not recommend using more than 20 pounds with the ankle weights - heavier versions could cause orthopedic problems.  If you outgrow your weights, you can try strength training machines. Another option is to switch to exercises that use your body weight for resistance, like modified squats, lunges and step-ups.  These exercises are outlined in my book Strong Women, Strong Bones.