You may check the backup log to find the reason of the backup failure and then take appropriate action to correct the error.
Once this is done, you can run an on-demand backup(if the Avamar server is in full access status), or wait for the next scheduled backup to make sure that error is not getting repeated.
I assume there is plans to add this to Avamar as it's standard for most of the Major Backup Programs out there.
Re-running a failed backup (or any failed task) is likely to result in another failure until you correct the root cause of the problem.
For some clients, taking a backup can consume significant time and resources. Automatically running all failed backups without correcting the problem would be like rolling a handful of dice, hoping for sixes.
Sandeep's advice to investigate what went wrong would be a 'best practice' to ensure consistent, reliable backups.