How do I turn my app into a template?

I am creating a food guide for a conference. So far it is working very well. I would like to use it for additional conferences. I know that I need a google sheet for the data for the other conferences, but how do I create a template app?

You can just make a duplicate of it by clicking on the three dots next to the link in your list of apps. You have a choice to keep the same sheet or create a new copy of it. You would then just change the data in the new copy of the sheet for the next conference.

If you want to use it as a template for a different Google account you could do this:
Under Settings and Privacy check the box that says “Allow anyone to copy my app and sheet as a template”.