My go-to for study skills:
https://www.nasponline.org/books-and-products/products/books/titles/hops-for-parentsThis is the parent version, but if the school were willing to support a general ed study skills group (maybe a "success skills for high school" group?), they could also use the teacher version.
In terms of buy-in--does she recognize that she has some skill gaps in work completion/submission? Because if she doesn't, or at least acknowledge that there is room for growth, there is no program or intervention that will work. Or, perhaps, engaging in a study skill-building regimen might be something that can be presented as an alternative to non-stop parental nagging.
-Self-monitoring, with a token economy or reward system for on-time percentage above a certain number. (E.g., a point each day, or by class, depending on how microscopic you need to get, for writing assignments down in planner, completion of work, handing in work)
