In a way that one has lapsed, because the revised decision is clearly more favourable than the original. In my example, there were four determinations making up the decision and only one was changed, so there remained an extant appeal against the other 3 aspects.
In your case, I’d say the appeal had definitely lapsed, because you have reduced the amount of recoverable OP. It depends on what the appeal grounds were, I think. If it was, ‘well, there’s official error and I don’t think I should be responsible for this OP’, then you’ve dealt with that and I think it gets a fresh right to make a new appeal. If the grounds were ‘I don’t think I’ve been overpaid at all’ then that is clearly something different and I’m not convinced it should lapse.
You could always refer it to FtT anyway for directions.
