You Can, but really, I dont see how..... When you harvest, and empty the pot, the coco is all bound up in the roots... It would take you hours to get the usable coco out of the bound up mess.... Just buy new coco...
reusing coco is fine have done 4 grows from the same batch.once u harvest let it dry out for 3-4 days,i then use a collender as a sifter to get the clumps of roots out.once thats done it gets soaked in regular ph water for a couple days to get out any unused ferts.dried again then add a bit of seedling mix and ready to use again.