When it comes to removing sap from clothing, I have had very good luck with Pine-Sol or Lestoil. It is worth a try.
By nema from Canton, MA
Removing Tree Sap from a Tent?
Removing Nicotine Stains on Clothing
Removing Tree Sap from a Vinyl Awning?
Cleaning Tree Sap on a Windshield
Blue Stains Showing Up on Washed Clothing
Removing Tree Sap from a Car