To reuse a survey's layout and design, turn it into a template. At the bottom of the list of Questions on the Questions Tab you can "Create a template from this survey". Give the template a name in the Template Name field and click Create Template.
The next time you create a new survey, at the top of the question list on the Questions Tab you will be able to "Start from selected template:". Choose the template name from the pull down menu and click "Use Template". Note that this will overwrite your new Title Page.
As soon as you have two questions in your survey, you will no longer be able to create a survey from a template as it will overwrite all the data in the current survey. Delete the existing questions and the option to use a template will reappear.
Edit or Delete a Template
There is currently no way to edit the content of a template without using it to create a new survey, making the modifications and saving the modified survey as a new template.
From the main page, you can follow the Survey Templates link on the left menu and see a list of all the templates you've created.
Use the trash icon to delete a template. Click on the template's name to change it.