Blot up fresh sap using white paper towels. Carefully scrape off any dried sap using a dull knife.
Dampen a white rag with a couple drops of dry-cleaning solvent. Read the solvent’s label for the specific amount of solvent appropriate for the sap stain and sofa's upholstery fabric.
Tamp the sap-stained area of the sofa with the solvent-moistened rag to dissolve the sap.
Continue blotting the sap stain with the solvent until all tree sap is dissolved. Fold the rag between blots, and moisten it with more solvent if needed.
Blot up any excess dry-cleaning solvent with a clean towel. Leave no solvent in the upholstery.