I think the fat in the breast milk might separate from the liquid if you refreeze it and rethaw. If I remember correctly, it doesn't thaw the same as when its frozen once and defrosted.
I wouldn't chance introducing a 6 month old a intestinal bacterial infection from slightly spoiled milk. 6-month olds have such delicate and vulnerable systems. Seriously, don't cry over spilled milk. You'll make more.
I love the suggestion of using the milk to make baby food and freezing that.
You can use formula over the next few days until you get your storage back up--your baby will be fine with a few days of formula. I think, given the choice between fresh formula or past-due breast milk, I'd choose the formula.