reset *diesel additive min level* warning

52 plate (late 02) 307 SW HDI 2.0l 110

I have filled the tank with the Eolys fluid, and now get fed up with the
warning every time I set off.
According to many sources of information, and also Haynes, this early model
should have a level switch built into the tank. In my case, it either is not
there, or the diagnostics ignore the full signal.
Is there any way, apart from the required arm and leg to Peugeot, of
resetting this?
Of course, I could just ignore it now I know the tank is full.