Isopropyl alcohol will easily remove it, and should be safe for clear vinyl coated leathers (most oem leathers are cleared).
To be safe, try some in an inconspicuous area first, and if you see the leather dye/ color coming off with the use of the alcohol, don't use it on the sap. Odds are your leather is coated and you'll be fine.
Sap is used to make shellac, and alcohol ( denatured ) thins shellac. It will work, but always test anything out beforehand to be sure... Cheers.
P.S. Even if your leather is coated, you can always dilute it 50/50 with water. You'll have to work it a bit more to break the sap down, but it will be a lot less harsh.