How do I add the same expense again?

Open the expense and tap Duplicate expense, or touch and hold it in the group and tap Duplicate. A new expense opens, filled in from it, in the same group. Nothing is saved until you tap Add.

The copy keeps what it was for, the amount and currency, the category, the notes, who paid and how it was split. It is dated today and gets that day's exchange rate. It has no receipt and doesn't repeat, and comments stay with the original.

Someone who has left the group is taken off the copy. If they paid, the copy starts with you paying, or, with several payers, shows how much of the payment is unaccounted for.

Duplicating isn't offered in an archived group, or for an expense that was deleted.