How to update after AppState has changed?

I have a Custom Widget (a RangeSlider) - and I need the values (min, max) on the screen I use the slider. So I am updating AppStates in the code of the RangeSlider (I figured that is the only way to get values back):

onChanged: (RangeValues values) {
                setState(() {
                  _lowerValue = values.start.round();
                  _upperValue = values.end.round();
                });

                // Update global variables
                FFAppState().filterPriceRangeLow = _lowerValue;
                FFAppState().filterPriceRangeUp = _upperValue;
              },

But now, when I have 2 texts on the page connected to the AppStates, they don't update:

How can I force the screen to update after changing of the AppState-values?

I found this, but that doesn't help me: https://docs.flutterflow.io/flutter/generated-code/flutterflow-classes#ffappstate

Thanks!