LS version: 3.23.3+200909

I have a survey that has expired and I want show anyone who has bookmarked the link a custom message with a link to point them to a new version of the survey (instead of the system default Expired Survey message).

How can I do this?

There is no feature for that. You will need move the expired survey to a different SurveyID and than create a short survey with a infobox or EndURL to the new survey.

I asked for a maintenancemode per Survey long ago. That never made sense to the developer scene here.
There is a nice plugin, but I don't think that work per survey ID.
extensions.sondages.pro/management/maintenancemode/

Let's think out of the box.

Do you host yourself? Then you could think about creating a htaccess rule and forward the old survey url to the new survey URL.