Asp.net: "New" Label On Unread Items

Question

I have a repeater that's bound to a data source. I then have users that view this repeater.

What is the best way to create a "new" label next to entries in the repeater that the user has not yet viewed. This scenario isn't like email where its unread until the user clicks on the entry; as there is nothing to click on.

I want it do be based on page load. If a user loads the page and there are 5 new entries, I want all 5 to be labeled "new." Then on a reload there are 6 entries (as a new one was added) I want the new entry to be labeled "new" and the other 5 to no longer have the label.

I think this is done with cookies, but I don't know how. I'd like to avoid adding a data table for this functionality.

I'm using ASP.net 4.0 and the built in SqlMembership provider if that matters.