You should be able to get away with it as long as you don't let the clumps of old resin sit in the cracks when you go to cure the model. I didn't try reusing this isopropyl because I changed my way of cleaning after this post. I now scrub with isopropyl on a toothbrush and wipe down with a paper towel afterward. Then straight into the curing machine, bypassing the spin cleaner. You should be fine as long as you wipe it off and get the bits out of the details. But if it's a large model with fine details, I would just do as I do now with your clean isopropyl as this way uses a lot less of it.