Unfortunately, without some re-programming, through third-party programs, it does not.
PrE's authoring is semi-automatic vs Encore's manual authoring, and being able to Link the end of a Timeline, back to itself, is just not part of the function set.
If you have Encore CS 3, I would do the final authoring in that program.
The other option is to set the DVD player to Repeat, which will effectively "loop" the disc.
The DVD player Repeat is a classical approach to looping DVD-VIDEO on DVD disc at playback.
However, please take a look at my blog how to to achieve this goal using Premiere Elements in conjunction with free programs such as IfoEdit and PgcEdit. It is easy to do.
We will be looking forward to your results whatever you decide.
The Encore route is the most practical for me.