If you have a meter, measure the OEM bulb resistance, then find a 5 to 10 watt resistor with close to the same resistance and install it across the bulb socket wires (or wherever).
Be careful with that. Most incandescent bulbs have a much lower resistance when cold than when hot. If you have LED operation problems, you don't need as much of a load as the cold resistance of a conventional bulb filament. I'd just check the wattage rating of the bulb and calculate the resistance to give you that power draw. If you don't know the math involved, a 12W bulb will be about 15 ohms hot and a 7W bulb will be about 27 ohms. Make sure the power rating of the resistor is at least as high as the bulb power rating, and be careful how you mount it -- it's going to get hot.
I'm with Brian, though, I doubt it's because of reduced current draw due to the LED lights (the voltage will always be the same, somewhere around 13.5). I suppose it's possible there's a burned-out bulb detection circuit (like some cars have) which is triggered by the lower current draw and eliminates regeneration to get your attention? Double-check that regen is set on first, though. Seems more likely that your setting somehow got changed. Or maybe something didn't get re-connected properly.
