To preview a revised listing, set VerifyOnly set to true when issuing the ReviseItem call to revise the listing. The response will include the calculated listing price change (if there is an increase in the BIN/Start price) but the values will not persist in the database.
Including VerifyOnly in a ReviseItem call is similar to using VerifyAddItem or VerifyRelistItem to test calls before you actually add or relist the item.