Please help with this problem of simulink?

https://picasaweb.google.com/100600576001599595108/MATLABSimulink#5834654212202423442 ,,,,,I have attached a simulink model and controlling code,,, please tell me how to keep the old values of 'b',,,

open_system('C:\Documents and Settings\admin\Desktop\test_Final.slx')
b=1;
for i=1:1:100;
   set_param('test_Final','StopTime', sprintf('%d',i));
   simout= sim('C:\Documents and Settings\admin\Desktop\test_Final.slx');
    pause(1)
        if i==6;
            b=10;
        end
end

[Walter Roberson]

duplicates http://www.mathworks.co.uk/matlabcentral/answers/59160-how-to-solve-this-issue