A new and distinct cultivar of Azalea plant named ‘;RLH2-2PA1S’;, characterized by its upright to outwardly spreading and mounding plant habit; vigorous growth habit and rapid growth rate; freely basal branching habit; dense and bushy appearance; relatively small evergreen dark green-colored leaves that do not abscise during the winter; freely flowering habit with remontant flowering during the spring, summer and autumn; large and ruffled semi-double and double flowers that are dark red in color; and excellent garden performance and temperature tolerance.