when I first got my phothos plant it wasn't growing, then I moved the cage near a window and now it has a lot of new leaves. So I guess just putting it in a fairly sunny spot will make it grow.
Pothos, like all plants, lives on light. Maine in winter has not got a lot of light, and the days are short. If you can increase the quantity of artificial light above the cage in winter anyway, then your plants will grow more. Keeping the plants close to the light will help too.
If you weren't keeping animals, you could also lengthen the days, but don't; that isn't good for tropical lizards. Give animals no more than 12.5 hr. days. Plants can make up for a decreased intensity of light by an increased duration of daylight. Nice to know if you're growing plants under lights without animals. I have my plant light timer set on 16 hr. days.
All other things being equal, higher temperatures, higher humidity, good fertilization, and physical support will all help them grow faster. Without light these steps are just going to result in weak, soft growth. If you can't add more light, be patient, they'll grow again more quickly in spring.