With that many miles on the current fluid, I suggest you're running the risk of dislodging burnished clutch material and sludge in the unit that can clog passageways and cause further problems. I'd try the reprogramming first. If you do drop the pan, retain the existing fluid and strain it. Change the filter and return the old fluid into the unit, just adding enough new fluid to top it off.

I have 339,800 miles on the original fluid in mine with no performance issues.

2002 X5 3.0 (gas) 339,800 miles
2014 428i 36,000 miles

2004 325i sold at 123,600 miles
2001 325i sold at 66,000 miles

1970 Firebird Under restoration