I often tie ideas for writing to books I’ve shared–not to use as prompts, but to generate conversations about ideas. Also, before my students go out to write, we have a couple of minutes for “turn and talk” for the kids to share with a partner what they think they might write about today. It seems to focus their work a bit. Certainly, there are those that still need more encouragement, but I do think this helps many students.
I’m anxious to hear other ideas, as well.

So I do many things to keep it going but two may really help…
First, we often end a session by showing someone’s writing on the doc camera and look for greatness and areas to grow. We have a rubric that kids use (in kinder but any grade could modify) and that we can use as a guide when looking for things done well and for areas to improve. We also look for ways to add on or ask questions about what they are doing.
Also, if you have a smartboard, one student who is working on writing can write on the smart notebook if you create a template. They love showing this off…
Kids are also motivated to work on projects from writer’s workshop or letters to different people… All sorts of opportunities…
Good luck!