Create one or more Templates to hold the 'master' copy of the forms - then copy / paste the forms from the template into the individual databases.
When you update your design elements in the template, the Designer task will update the other databases. I think by default Design task runs at 10PM, but you can run it manually, or update the design of any database at any time manually.
This is basic design of Domino/notes - system databases and mail files all typically inherit their design from a template. When you update Domino versions, many of the Domino databases are updated via design changes to the Templates.