If you view the browser source code you will see '&' It is still there just not visible in the browser as should be.
But if I understand your problem, you wish to reinsert the edited data back into the DB with 'amp;' still intact.
First just double check what I have said above is correct.
Then are you using PHP by any chance?
If so try calling function htmlspecialchars() just before inserting the text back into the DB.
Failing that, the only thing I can think of is runnng the text through your own function using string functions to add the additional 'amp;' before re-insertion