I applied crabgrass preventer in the spring, but still have a lot of crabgrass

It should be applied when the soil temp is 55 F, usually when the lilacs bloom, as a marker.
https://kglandscape.com/when-to-apply-crabgrass-pre-emergent-in-mn/
https://apps.extension.umn.edu/garden/diagnose/weed/idlist.html