Wow - what a great problem to have! Opposite of the usual logic (how do I lower it...)
Others with more experience will hopefully chime in with specific part suggestions. I can share that Armory Craft has a range of springs to reduce trigger pull, and may have versions that increase it. Example here: Sig Sauer Trigger Pull Reduction Kit P220 P224 P225A1 P226 P227 P228 P229 P239 | armorycraft I would call Milos and ask - he either has what you need or can suggest options to solve for it. Either way, you will likely find the call worthwhile.
Good luck!
Others with more experience will hopefully chime in with specific part suggestions. I can share that Armory Craft has a range of springs to reduce trigger pull, and may have versions that increase it. Example here: Sig Sauer Trigger Pull Reduction Kit P220 P224 P225A1 P226 P227 P228 P229 P239 | armorycraft I would call Milos and ask - he either has what you need or can suggest options to solve for it. Either way, you will likely find the call worthwhile.
Good luck!