To reevaluate the Formula of a Formula column, one can write
col<<Eval Formula()
Is there a similar command to re-evaluate a Transform Column?
Eval Formula doesn't seem to work here - Tcol1 still shows a curve with ::scalingFactor=1:

Names Default to Here(1);
dt = Open( "$SAMPLE_DATA/Big Class.jmp" );
gb = dt << graph builder();
::scalingFactor= 1;
tC = dt << transform column ("TCol1",Formula( :height * ::scalingFactor ));
gb << variables(X(:height), Y(tC));
::scalingFactor=5;
tC << Eval Formula();
tC2 = dt << transform column ("TCol2",Formula( :height * ::scalingFactor ));
gb << add variable({tC2, Role("Y"), Position(1)});