As a follow up, if your LOB data is smaller than 8000 bytes, you could of course convert it to varchar(8000) and do a replace on that.

To see an example how to do replace using the UPDATETEXT have a look at http://sqlserver2000.databases.aspfaq.com/how-do-i-handle-replace-within-an-ntext-column-in-sql-server.html

It may of course be easier to write a small external application (text, ntext and image columns are really a pain)

Regards,

Andras