I guess you use SSH-keys as authentication? Reauthentication and key exchanges happens all the time during the SSH protocol, so having a Active session is secure enough.
Another thing is confirmation, eg, you want that the user really wants to commit a action that might be irreversible. Lets say deleting something.
To solve this problem, I would suggest you simply show a random 6 digit code on screen and ask the user to retype it to signify a "YES". (and treat as "NO" if the 6 digit code was incorrect or no code is written.)
Are you really sure you want to delete the database records_2013.db?
If NO, just press ENTER now.
If YES, type the following code - 193619 - here, and press ENTER: _
This then solves your problem perfectly, since the SSH server/client would make sure it has a valid authenticated Connection to the server, which means a malicious user cannot hijack a authenticated SSH session, and the random confirmation code, then ensures the user does not, by mistake, commit to a dangerous operation.
Note that this code is not considered to be a captcha, so it wont hinder automatic submissions. But reauth by ssh-keys wont solve that either.
The code is just there so the user stop and Think really carefully if he want to proceed Before proceeding.
The reason banks use some reauthentication scheme, is that sessions can be hijacked since HTTP/HTTPS is a stateless protocol (Connection are closed after the page are sent, making it hard to use the underlying protocol to do session authentication), but also for the second reason, to prevent users from by mistake, sending Money somewhere they did not intend.