If you began homeschooling because your child was considered 'at risk' and was becoming more and more 'at risk' every day, here is a tool that you might find helpful. I can come across a program designed for use in school districts where there are a large number of at risk students. There is no reason however, that homeschoolers cannot use it too. (Of course, you may want to check the content for worldview vs. Christian view. The materials are available in multi packs and single servings too!
"The ELA ASP (Academic Support Program) is a complete modular package for improving academic performance when students are at risk. By integrating instructional strategies with test practice, it is a powerful solution for the great majority of striving students who aren't served by test practice alone, while being flexible enough to "back up" as different kids need it, and has been designed around the IRA/NCTE standards."
The English and Language Arts program costs $295.00 for grades 9-12 and from what I can tell, by looking at the preview downloads, it is a good guide for what your 9th -12th grade student needs to know. For children who just need to round out their highschool homeschool experience, you may want to try out 300 Lessons In Art for 7-12 graders, or Activities in Musical Composition for middle and high school students. The prices for these enrichment programs are very reasonable.