Hi, from Lahore to Nanjing, there is no flight on Mondays and only joint flights on the other days. Here is one of the joint flights schedule on Sep.6 for your reference:
Lahore – Beijing PK852 2145/0705
Beijing – Nanjing MU2802 1030/1210

From Islamabad to Nanjing, only connecting flights are available. Per your request, flights with transfers at Beijing are available on the 6th, 10th and 13th of this September. And flights transferring at Hong Kong are available on the 8th and 11th. On the sep.7 and Sep.9, only flights with two transfers are available. Considering the flight time, transferring at Beijing will take shorter time, and you can take the flight schedule below for reference:
Islamabad - Beijing PK852 2330/0705
Beijing - Nanjing CA1817 0900/1050

The airfare of international flights varies day to day. You can consult the booking agency or airlines after you decided your travel date.