You cannot upgrade the CPU -- it's soldered to the system board.   If you need a faster CPU ( or a newer generation), it's new system time.  
Is it worth to upgrade my CPU? Currently i9-8950HK 2.90GHz. I would like to get up to 3.5GHz or faster? Also looking to upgrade ram from 32GB to 64GB (would love 128GB). Or buy a new laptop?Windows 10/Intel Core i9-8950HK CPU 2.90GHz/32GB memory/1TB SSD
XPS 15 9570, upgrades or new Laptop?