In the gradebook for the previous course you need to click on the gear at the top. Check the option to show inactive enrollments. Now go to the wrench and export grades; save the file. You probably want to uncheck inactive enrollments before leaving.
Open the exported grades. Delete all of the student rows except for this student.
Go to the gradebook for the new course. Click on the wrench and select import grades. Choose the exported grade file (it should only have the one student). As long as the activities are the same the grades will show up in the new course.