How does double jeopardy work here?
Do you mean with regards to the impeachment trial ?
yea
I'm sure benji will have a ten paragraph care post for this and don't take my word on it but my general understanding is that it doesn't apply. The Senate only decides on the political matter of removing from the office, not on any actual civil or criminal sentencing that would, I suppose, have to be prosecuted in court once the former President would come back to the general citizenry.
Or maybe you mean within the Congress and Senate, for a second Impeachment procedure ? I wouldn't know but in most cases it doesn't seem it would make sense politically to go again at the same canard.