Hi Musicluvr49. In your mind of course. Visualize it, go thru it , see everything. There is a book by Harriet Brower who interviewed many of the great concert artists who where performing during the first part of the 20th century , Hoffman, Rubenstein, etc. and many of them used this technique of playing pieces in there mind. My Teacher insists that i memorize all my performance pieces completly. That is I know them so well I have to be able to write them out. It works for me and im only passing on as a suggestion things that I do. Im not saying it works for everyone.
Cheers, Becky