You need to start moving some of your constant data into far memory using the "far" keyword in the declaration.
There's a good discussion in this forum question: https://www.digi.com/support/forum/29188/out-of-constant-data-space
One of the solutions for that poster was to list "ROOT_SIZE_4K=6U" in the project's macro list. Be sure you have enabled "Separate Instruction & Data" space in the compiler options as well. You can take that macro up to 9U, as recommended in Device_Cloud.lib:
If defined, turns on debugging printfs for all Device Cloud subsystems. This can cause shortage of root constant space. If so, add ROOT_SIZE_4K=9U in the project defines box, and turn on the separate I and D option in the compiler settings.
And this Forum question provides some additional background information on memory configuration: