nbars = 20;
data = Array[0 &, nbars];

Animate[
 data = RandomInteger[1, nbars];
 BarChart[data],
 {n, 1, 5, 1}, AnimationRepetitions -> 1
 ]

nbars = 20;
data = Array[0 &, nbars];

Animate[
 data = data + RandomInteger[1, nbars];
 BarChart[data],
 {n, 1, 5, 1}, AnimationRepetitions -> 1
 ]