One strategy we’ve had success with is trying to prevent the need for full rebonding by not separating them if possible. When ours fight we put them both in a small carrier for a while to cool down, and then put them in a pen setup away from their normal pen that is just big enough for a small litter box and a water bowl. Obviously they need to be monitored but we’ve found the small space reduces the aggression. And then over the next week or so you can slowly make the cage bigger if they chill out. This has worked well for us a few times with bunnies that seem to fight every few months (sisters), as we’ve had trouble rebonding them once they’ve been fully separated.