First I'd recommend you check out the Flow Community as that is where the Flow PMs are telling folks to post. To answer your question, I assume you when an item is edited or created, like on the old SP2010 approval workflow checkboxes to end if an item is changed? As far as I know the Flow shouldn't break, and it would just another instance of the Flow if you change the item (depending on your trigger). But it could send things into an infinite loop so it just depends. There should be a status or some field that dictates the state of the item, and the Flow checks that status before doing anything to validate the approval is needed or not (e.g. only start approval if status = pending approval).
Did you already have a Flow in place, or were you just asking ahead of time? If you have a Flow made, please provide more details on your process so we can try and provide a more concise answer. Thanks!