There are two kinds of repetition that have turned up.

One is a Future Boost that happens on a regular schedual, so being able to set it up as weekly, fortnightly etc. would be useful.

The other is a Boost that has passed and been ticked off, e.g. a movie night with friends where someone says "we should totally do this again!" In this case a Repeat and Edit button on past Boosts would be useful.