Improve motivation in the final part of a project based course Fellow educators,

I am teaching a project based course composed of two parts. The first half of the course focuses on basic concepts and activities that serve as preparation for the second half where students work on a project. The project is based on a grading rubric and, for students, it is very easy to evaluate their own progress. 

Lately some students started leaving class earlier. The early leavers are actually the best performing ones and have already accomplished the minimum project goals. Thus, they are already approved in the course even though we still have one month left... (&lt;-- this sounds like a problem...) 

My question is: how to improve the "end-game" of project based courses to avoid students leaving early and help them to stay motivated?
In my program, we have a year-long culminating capstone project which has a format that might work well for you.  Traditionally, high school seniors in this area of the world catch a disease called "senioritis" that prevents them from doing a lot of work as they enter into the last few months of high school.  It's a highly contagious disease, though once caught, you often gain a subsequent immunity (such as in college or graduate school).

We

The format of the year is:


Choose projects
Work towards completion
Give final presentations to outside judges
Final cleanup and submission


Here are the details for steps 2-4 that make this all work:


Working towards completion is done using milestones.  The students decide what the next logical part of their project is, and negotiate with the teacher what they will accomplish by the next check-in date. (They also negotiate what the next check-in date will be).

In my experience, I have to dial my students back more often than I have to push them forward. Students often have big ideas, and little sense of how long those ideas will take to enact.

I keep a public calendar of which groups I will need to see each day. With any extra time, I check in with active groups to see if they need any help.
Final presentations

We rehearse our final presentations in small assignments during the weeks leading up to the big day, and I give critiques to help improve the presentations as we go. 

On the big day, we use a big(ish) venue, invite the underclass CS majors, and have a panel of outside experts as judges.

It is extremely important that the teacher not be an evaluator for the final presentations. This keeps the pressure up, both on the students, and on the teacher! 
Instead, outsiders are brought in (and provided a grading rubric!) who will judge the final projects and finally presentations on their merits.  Some of these outsiders may still be from our institution, but not all of them, and no one who has been in any way involved in a project.

These final grades are averaged together, and will eventually be mixed in with the milestone grades.  

But first, the student is given... a zero!

Well, not really. But the grade they receive from the judges is provisional. They have to finish up the last pieces in order to receive this grade.
Final cleanup and submission

This is the phase, usually about 2 weeks after the presentations, during which the students have to do their 'i's and cross their 't's. Is the project actually finished and documented? Do the clients have the access and support they need to actually use them? Are the projects actually submitted on GitHub to the teachers? Have the students filled out an end-of-program questionnaire?

Once those pesky boxes are all checked, students are finally awarded the grades from the presentations.


Put all together, all of these moving parts seem to prevent senioritis completely. The high fliers want to put their best foot forward for the outside experts. The strugglers work very hard to make sure that their project actually comes together before the big day. The final checklist means that I am not left with a bunch of 99% completed projects at the end of the whole process.