Yes:

1) Change the preferred setting so that the new template is preferred.

2) Switch the archive template settings.

I've been redoing my main date-based (monthly) template by creating a test template. I'm saving the test pages with another name but now I'm getting ready to make the new template (and pages) replace the old one.

In my Blog Config area under Archiving, I've got the two date-based templates. My present one is the "preferred" and the Archive File Template field is blank. The test template, however, does have the following in the Archive File template field:

When I'm ready to make the test live, should I just reverse the Archive File Template fields (at least temporarily until I make sure all is well, then I can eliminate the old template)?