How do I make a portion of a GUI code run again even though it is nested in a while loop?

I made a code to handle a micro controller unit connected to a conveyor set-up. Most of it works fine but a part of it only activates at the beginning when i press the GUI's "START" button. Although it is nested in a while loop already it doesn't run again and the conveyor it controls stops after the condition is met the first time... here is my code:

 if queueSensor == 0

       if numel(eggQueue) <= 4

           cRamp = 1;

       else    

           cRamp = 0;

       end

    end

-----------------------------------------------------------------------------

here is the complete START button coding:

 while procStat == 1

    %send serial data command/request

    sReq = sprintf('DCOM_%d%d%d%d',cRamp, cQueue, cSeg, cBlower);
    fprintf(s,sReq);
    cBlower = 0;
    %read serial data

    [dummy,count] = fscanf(s,'%c');

    if count >= 8 

        sIdx = strfind(dummy,'DATA_');

        if sIdx == 1
           %valid data
            uRead = sscanf(dummy(6:8),'%u');

            queueSensor = uRead(2);
            segregatorSensor = uRead(1);

        end

    end

    %process serial data

    %get snapshot
    data = step(videoDevReader);
    lab_Image2 = applycform(im2double(data),cform2);

    imshow(data); drawnow;

    b = lab_Image2(:,:,3);
    bw_image = im2bw(b,0.15);
    bw_image = imcomplement(bw_image);
    bw_image = imfill(bw_image, 'holes');
    bw_labeled = bwlabel(bw_image, 8);     % Label each blob so we can make measurements of it
    blobMeasurements = regionprops(bw_labeled, bw_image, 'Area');
    allBlobAreas = [blobMeasurements.Area]; %get areas
    allowableAreaIndexes = (allBlobAreas > 9000) & (allBlobAreas < 30000); % Take the small objects.
    keeperIndexes = find(allowableAreaIndexes); 
    keeperBlobsImage = ismember(bw_labeled, keeperIndexes); 
    bw_image(~keeperBlobsImage) = 0;  % Set all non-keeper pixels to zero.

    if numel(keeperIndexes) > 0

        if detectionFlag == 0

            bw_labeled = bwlabel(bw_image, 8);     % Label each blob so we can make measurements of it
            blobMeasurements = regionprops(bw_labeled, bw_image, 'Eccentricity');

            foundE = [blobMeasurements.Eccentricity];

            if numel(foundE) > 0

                detectionFlag = 1; 

                if foundE(1) < eThreshold

                    eggMatrix = [eggMatrix 2]; %female
                    eggQueue = [eggQueue 2];

                else

                    eggMatrix = [eggMatrix 1]; %male
                    eggQueue = [eggQueue 1];

                end    

            end

        end    

    else

        detectionFlag = 0;

    end

    if queueSensor == 0

       if numel(eggQueue) <= 4

           cRamp = 1;

       else    

           cRamp = 0;

       end

    end

    if segregatorSensor == 0 

        procQueue = 1;

    end

    if procQueue == 1

       %process queue 

       procQueue = 0;

       cSeg = 0;
       sReq = sprintf('DCOM_%d%d%d%d',cRamp, cQueue, cSeg, cBlower);
       fprintf(s,sReq);
       fscanf(s); 

       if numel(eggQueue) > 0

           if eggQueue(1) == 1

            cSeg = 1;
            cBlower = 0;
            sReq = sprintf('DCOM_%d%d%d%d',cRamp, cQueue, cSeg, cBlower);
            fprintf(s,sReq);
            fscanf(s); 
            pause(0.5);

           else

            cSeg = 0;
            cBlower = 1;
            sReq = sprintf('DCOM_%d%d%d%d',cRamp, cQueue, cSeg, cBlower);
            fprintf(s,sReq);
            fscanf(s); 
            pause(0.5);
            cSeg = 1;

           end

            eggQueue = eggQueue(2:numel(eggQueue));

       end 

    end

    maleDuck_idx = find(eggMatrix == 1);
    femaleDuck_idx = find(eggMatrix == 2);

    maleDuck = numel(maleDuck_idx);
    femaleDuck = numel(femaleDuck_idx);

    tTimer = toc(handles.start);
    set(handles.txtTimer, 'String', sprintf('Total Elapsed Time: %02d:%07.4f',floor(tTimer/60),rem(tTimer,60)));
    set(handles.txtCounter_Male,'String', sprintf('Male: %d', maleDuck));
    set(handles.txtCounter_Female,'String', sprintf('Female: %d', femaleDuck));
    set(handles.txtCounter_Total,'String', sprintf('Total Duck Eggs: %d', maleDuck + femaleDuck));
    set(handles.txtCounter_Queue,'String', sprintf('Eggs in Queue: %d', numel(eggQueue)));
    drawnow;

 end

set(handles.btnStart,'Enable', 'on');
set(handles.btnStop,'Enable', 'off');

   sReq = sprintf('DCOM_0000');
   fprintf(s,sReq);
   pause(1);

fclose(s);
delete(instrfindall);
imaqreset;