Yeah, it’s a thing of practice to be able to hold your breath for multiple heavy reps without taking an immediate and unscheduled nap. Work on it, as it will help you stay tight and organized, but don’t go overboard.
If you’re setting up with straps, I would just get a good brace going at the top, stay pressurized, but keep breathing down into the tight belly as you’re setting up. Then, when you’re all strapped up and ready to get tight, take a big snuff of air in through the nose to increase the abdominal pressure to DEADLIFT LEVEL!
In terms of multiple reps, you want to be tight and loaded before each rep, but if you break position I would stand back up without the bar, reset the brace, then get your hands back on it. If you’re chaining reps up and staying in control of them you should be able to keep tension rep-to-rep. In this case, I would rebreathe at the top when necessary, and make sure to keep the belly on tension while doing so. It will look like a breath out, and a big snuff in.