Celeste, This may be long winded, but here's a few comments:
These tips will help you diagnose the most common causes of overheating and remedy them fast.
Check your water circulation. The easiest check is to start up your bike with the radiator cap removed. As your engine heats up, the thermostat should open and you'll immediately notice the flow of fluid through the radiator top with a torch. If your engine overheats and you have no fluid moving through the radiator top section, you definitely have a circulation problem.
After you let the bike cool down, you need to determine whether your thermostat or pump is at fault.
First, remove the stat and try again, you should see flow at the radiator immediately, if not – suspect the water pump.
If you suspect a thermostat fault, remove it from the engine and place it in a pan of water. Check its specs for opening temperature in the service manual (temp may be stamped on the thermostat - usually around 195oF) and begin heating the water. Note the temperature it opens with a thermometer and check it against the specs. If it opens late, partially, or not at all, it is most likely the cause of your problem.
If the thermostat checks out, but you have no flow to the radiator your water pump is bad. Unfortunately, there's not too much you can do except replace it, it runs off the cam and are not normally an issue.
Check your hoses - older hoses sometimes collapse from suction and can inhibit flow at higher speeds.
If all this comes to no diagnosis of the fault, you may have a combustion gas leak to the water system (head gasket?), therefore pressurizing the water system and blowing the water out. A radiator company can add a dye to your water which will detect carbons by a change of colour.
One more thing, remember that the fuel mixture is altered by the ECU which picks up a sensing voltage from the water temperature, so if you say the temperature always reads high, then the fuel mixture will be weakened to compensate. A weak mixture creates more heat!
One last comment I have is that as you have previously flushed the system out and noticed an improvement, it could be that some of the previous radweld emulsion has moved through the water system and could have built up in the radiator. Try taking off the rad and back-flush it with a hose pipe, or take it to a radiator reconditioner company to have tested..