FSRS4Anki Helper is an Anki add-on that supports FSRS4Anki scheduler. It has five features:

• Reschedule cards based on their entire review histories.
• Postpone due cards whose retention is higher than your target.
• Advance undue cards whose retention is lower than your target.
• Balance the load during rescheduling (based on fuzz).
• No Anki on Free Days (such as weekends) during rescheduling (based on load balance).

• Anki version >= 2.1.55
• Enable V3 Scheduler
• FSRS4Anki scheduler version >= 3.0.0

The easiest way to install FSRS4Anki Helper is through AnkiWeb: https://ankiweb.net/shared/info/759844606

Set parameters for your FSRS4Anki scheduler. Then click Tools -> FSRS4Anki Helper -> Reschedule all cards (Ctrl+R):

If you only want to reschedule a specific deck, you can click Reschedule cards in deck.