Student research proposal for project continued from past year
Consider your audience, they will need reminding what this is all about. As this is a continuation of last year's work, most of the initial description (placing the problem in context) is still relevant. The goals and results of the previous work should be summarized, after that you have to state this year's goals.

Yes, the document will probably somewhat longer than the first one. But that is to be expected, you know the problem better, and are not only describing the problem to be solved but also showing earlier results (thus reinforcing your ability to see the project through).