How to change the gMotorVars.MaxVel_krpm while servo motor is running motion profile

Hi every one!

Good Day.

I am using MotorWare18  proj_lab13b , (for servo motor).

I need to change the gMotorVars.MaxVel_krpm while servo motor is running motion profile. how to do that ?

what I have done is ...

step1:gMotorVars.PosStepInt_MRev=100;

step2. gMotorVars.PosStepFrac_MRev=_IQ(0.0); 

step3:gMotorVars.MaxVel_krpm = 0.010;

step4:gMotorVars.RunPositionProfile =1;

then motor start to spin.so what I need is to change the speed of it whenever I like   

for example:

step6:gMotorVars.MaxVel_krpm = 0.200;

then 

step7:step6:gMotorVars.MaxVel_krpm = 0.070;

but sadly the speed  does not change when motor is running motion profile .

would you please tell me what to do?

thanks for attention

Regards.