Terminal - how to restart session after inadvertently exiting?
At this point, there's no way to get the tab back. The terminal session is closed, and it no longer has a TTY. There's just no way to reference the tab in order to do anything clever. I'd suggest adding this function to your .bashrc or .profile so that you won't have the issue in the future:
exit() {
    read -t5 -n1 -p &quot;Do you really wish to exit? [yN] &quot; should_exit || should_exit=y
    case $should_exit in
        [Yy] ) builtin exit $1 ;;
        * ) printf &quot;\n&quot; ;;
    esac
}

or, for those of us who use the Z Shell (add it to your .zshrc):
exit() {
    if read -t5 -q &quot;?Do you really wish to exit? [yN] &quot;; then
        builtin exit $1
    fi
}

It's a nice little barrier between you and that annoying exit command! Lord knows I've done the same thing many times in the past.