You could use CSS to keep the same layout and design, or you could use the "save as" feature and simply save your index as a new name.
One thing though ... the way you are doing this is the hard way. Every new page you create will mean going back to every other page and updating it to include a link to the new page, resaving that page and reuploading to your server.
Is there some reason you aren't using a CMS like wordpress, joomla, or drupal?
You could learn how to create templates for them. This way you're simply creating a page one time and the CMS will place the appropriate information into your template.