They can't. She was acquitted. The fifth amendment protects against double jeopardy.

Can't they do another trial when new, damning evidence is uncovered?

Also, a conviction in state courts does not count towards federal courts, as addressed by the Rodney King trials. If she was convicted in the state courts, there might still be a chance.

perjury against federal officers?

It doesn't matter. Unless there was something else they could slap something on her that she wasn't tried for at first, she can't be tried again.

There are so many "loophole" laws that double up on other laws it doesn't really matter.
That's why when you commit a crime they charge you with 40 other things...