some people say you can if you’re taking a hose off and then refitting in the same place. But once the olive is on and squashed, I can’t see how you’d get it off to refit anyway.
The inserts – yes, but you have to cut open the hose to get to it, and given the olive and insert comes as a package I’ve never bothered other than to find out how to do it. I suppose if there was a source of olives (are they a standard size) then it might become worthwhile but at £2 for a set how much can you save?
As for cutting without a stanley knife. I’d risk using the wife /mum’s best kitchen knife, it’s only plastic. Cable cutters, I think you may squash the hose too much.
If you have to ride in the morning, do it with the hoses too long rather than try a reuse bodge and F it up.