Extruder Temperature shown wrong in repetier

Hey joint users,

i had a Problem last week that, the extruder was blocked by the used Filament. I build the Extruder apart and unfortunatly I demaged the Thermister. So I changed this one with a new NTC (100k as required) and first all seamed to work proper. When I start Repetier, the temperature of the Extruder is about 19-20 °C which seams to be right. As the printing starts, the Extruder is heated, but the temperature on repetier shows always the same temperature. I already checked if the shown temperature is just not updated, but it seams to work proper. The problem is now, that the printing w’ont start, due to the fact, that Repetier always displays a wrong temperature.
Does anyone know, where the problem may be? Do I have to change something in the firmeware?

Kind regards,
Fetsch92.