Is your sand a deep sand bed or just for aesthetic purposes? If it less than 1/2" like mine, I would vacuum it real good first and reuse it. It still has a lot of beneficial bacteria in it that will take a while to reestablish if you toss it or let it die. In this case, you would transport it in 5 gallon buckets with salt water.
If it is a deep sand bed, there is a lot of pent up PO4 that will be released when you disturb it. This will require washing the sand and if that's the case, you might be better off going with new sand. The old sand will probably create a cycle when you set it back up. You could try washing it real good with salt water but no telling how much PO4 is locked up in there (if it is a DSB) and could be released. SPS and PO4 don't get along. I use a bacteria called SmartStart Complete. I have used this on many new set ups with dry rock as well as tanks that were an absolute mess that we took down and cleaned up. I have never had an ammonia spike or other nutrient spike when using this bacteria. I would acquire some online and add that to the tank when you set it back up to prevent any adverse effects of disturbing the current balance.
How long between take down and set back up? Hopefully not more than 4-6 hours. I would try and transport as much water as possible (at least 50%) and reuse that too. The less you can disturb, the better.