Note your K1200LT has a dry clutch like a car has.
A slipping clutch can have four suspect areas to look at.
1. Engine rear main seal leak
2. Transmission front seal leak
3. Hydraulic clutch slave cylinder leak
4. Clutch just worn out
You can make a quick determination if it is #4 - drill a 1/8" hole in the bell housing between the transmission and the engine. If no oil comes it is number 4. The small hole you drilled will not be a problem - in fact it is a good tattle in the event you have leakage in the future.
If oil comes out it is either 1-2-3. If the oil looks real black like motor oil it is #1.
If the oil is red it is most likely #2 transmission fluid - that is if you use red transmission fluid. If the oil is yellow to clear it is most likely #3.
Mine was black and I lost a rear main seal. If you are on the road this is a major repair because no mater what the cause you are going to need to get the wheel off, drop the rear drive, take off the swing arm, and pull the transmission. At some point on this process you will determine the cause of the slippage. Then you are going to need to pull the clutch out and inspect what parts you are going to need to be replaced or cleaned and put back.
I caught mine very early - spotted a single drop of oil on the ground under the bike. I really did not even need to replace the clutch but I did - all the rest of the parts were cleaned up and put back together. Took me a long week end by myself!
I believe the price to do this in a BMW shop will range from $1500 to $2500 with the bike laid up for 1 to 2 days.
In either case if it is now slipping it will not get any better if the source of the slipping is wither #1-2-3 and continuing on a trip would be risky. But if you need to keep moving drive a lower speeds and rpms and shift as little as possible. You risk is you may get stranded or ruin more parts like the clutch housing or pressure plates and misc clutch parts. Drill that hole and see what comes out for starters.
Sorry for the bad news . . .