Well first of all you are probably using a NVARCHAR or NTEXT field in your database already. Hence the content of field is encoded as Unicode.
It would be nice to assume that your original posting form posted using UTF-8 encoding and your receiving page had its Response.Codepage set to 65001 so that the incoming string is stored in the database with fidelity.
If the foregoing is true then to send the content to the client using a new charset it would be a simple matter of setting the page codepage correctly, for ISO-8869-1 we use the codepage 1252. With the codepage set to 1252 any data sent using Response.Write
will be converted from the native Unicode to the 1252 codepage.
However, it is also quite possible for you to have got by with corrupt data being stored in the DB but it all looking fine in HTML. See my answer here to an older question for detail on how that might be. That same answer contains the steps need to repair the data in the DB. After that setting the output codepage should be sufficient.
Note that the ASP file itself should be saved as Windows-1252 and not UTF-8 otherwise any none ASCII static content in the file will be accepted incorrectly by the client.