Spelling help with dysgraphia?

My 7th grader has a diagnosis of dysgraphia. He was privately tested in 5th grade, and has no other diagnosis. Since getting him some supports, he's progressed so much! His handwriting is now legible, and he can use a laptop with spell check to write well (thoughts and finally flowing into words!). His spelling though, remains very poor, and I've run out of ideas to help him. With spell check, he's lost all motivation to learn how to spell. The usual advice I get is "just learn to type and use spell check", but I feel spelling is a life skill, and I think he'd have an easier time in High School if he can spell a bit better. Has anyone worked on spelling with dysgraphia? What worked? What doesn't? Any tools or resources you can recommend?