It's possible - but I would be suspicious of anyone who advertises more than a 21% capacity improvement for the CE 04 - here's why:
The 60ah modules from the C Evolution that they are upgrading from were designed 10+ years ago (2012), for a release in 2014. Two years later (2016), BMW offered an upgrade to 94 Ah - so my guess is they already had this possibility in mind when they built the frame. I don't feel like cell technology has progressed enough since the CE 04 was designed 4 years ago. I'd be very suspicious of anyone who advertises an ability to do this with the same safety and reliability margin that BMW builds into its packs.
Going by the historical average of 6% density improvement in Lithium Ion batteries per year, I suspect the most you'll be able to get is a 21% improvement in range without significantly modifying the CE 04 frame and handling characteristics. With the C Evolution rebuild, using this 6% rule calculation, it seems reasonable to go from 94 Ah to 140 Ah between 2012 and 2024; with the CE 04, you'd only be able to move up from 60 Ah to 76 Ah using that same calculation.
On a somewhat related note - I do know of at least one reliable vendor that does this service for eBikes out of Nevada:
https://ebikemarketplace.com/
