A full read would do it, but I think the safer recommendation is to just use a small hdd for external storage. Anything else is just dealing with mitigating factors

Thanks! I think you're right about just using an HDD, but for my portable SSD situation, after a full read of all blocks, how long would you leave the drive plugged in for? Does the refresh procedure typically take a while, or would it be completed in roughly the time it would take to read all blocks?