Broadcast history

The History tab lists every broadcast you've sent, newest first, with the audience, the send time and how many phones it reached.

Reading it

Reached is the number of phones the message was delivered to. It's lower than your member count because some guests uninstall a pass or turn off notifications.
A message with a sharply lower reach than the ones around it usually means the audience was one card rather than everyone.
To judge a broadcast, look at Tracked revenue by day on the Overview for the day of the send and the day after.

There's no resend button on purpose. Copy the wording into a new broadcast and change the deadline, so guests don't see the exact same message twice.