Well CNG on motorway, between Isloo and Lahore is available as follows:
Chakri service area
Balkasaar (Chakwal) interchange but you have to go out of motorway
Kalar Kahar service area
Bhera service area as well as out of interchange
Kot Momin but again out of motorway
Pindi Bhatian; out of motorway
Sukheki service area
Shiekhupura; out of motorway
Please be mindful that up to Pindi Bhatian is the Potohar/Faisalabad range with CNG not available from Thursday morning till Sunday morning while the rest are in Lahore region with CNG loadshedding days from Monday morning till Thursday Morning.
Probably if you start on Sunday than you can get it right upto Lahore; Get the tank filled up on same night in Lahore so it can easily bring you back till Pindi Bhatian from there on it should not be a problem till the end.
Cant think of any thing else for Two consecutive days. In case you are able to do some thing better then do share with every one here.
Good Luck