Aly - it's not too late - catnip is part of the mint family, which is so hardy a p[errenial as to be virtually a weed - Dad's yeard is fragrant when mowing because the oregano (mint relative) the peppermint and the "black mint" have all overgrown their boundaries, so get mowed!

Repot them in a bigger pot with more good dirt - potting soil would be fine. If they are tall and stringy looking, you can pinch them back and they should recover just fine.

Damp, not drowned! They don;t like having "wet feet" - would you? They're probably root-bound in the teeny pot they're in, so are vulnerable. Bigger pot, more dirt and some sunshine ... let us know how it goes!