I first rinsed out the pouches and saved them in the freezer, until I was ready to refill them. Since I didn't have a funnel that small, I made one from the box the pops came in. Just cut out a rectangle of cardboard, twist it into a cone and tape it. Then it's easy to fill the pouches. Leave an inch or so headspace. I used a clothespin to pin the tops shut, then carefully stood them upright in the freezer. If you're very very careful, you don't even need to pin the tops shut. Just stand them up so they can freeze without spilling.
So the next time a pop gets left sit, don't dump it out, make some of the tastiest freezer pops you will ever have from FLAT SODA POP!