So I am working on a map, my most successful, as I got an object to show up, but when I reskin something, the reskin won't show up. In fact, even though there is no trace of the old skin, it's still there. How do I fix this?

Clean. When changes don't show up, it's typically because the munge doesn't see a difference between the old version and the new version.

Manual or Visualmunge?

Full, manual cleans never hurt anyone...