My two cents - go for a new bike. You’ll absolutely love Di2 and I’m certain a bike can be made to fit you if you measure stack and reach, then get something comparable. I had the same problem with my 2012 Domane - I simply wore it out, and a new Di2 groupset is crazy expensive.
So I just bought a new Domane SLR 7 with Di2 and 32mm tubeless tires. Goofy smooth and so much fun to ride.
Hey, you’re still getting out there, hammering it out. You deserve to treat yourself!
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Ride hard and ride on......