maybe try looping the operation you are performing with a pause(time) in the loop and a number of iterations that result in the desired time interval. put that in another loop that updates the variables each iteration and each time the inner loop finishes it'll grab the next variables and go at it again. its hard to tell exactly what you want without some more detail but maybe something along the lines of:
plot(x,y,'o');xlim([1 5]);ylim([0 50]);
This,for example, would draw a line with the first set of rand numbers for 5 X 1 seconds, then switch to new rand numbers and go for another 5 secs, etc., 10 times. Control your wait time on each set of variables using j and pause time.