Kallis and Donald made the call during a cricket breakfast function which was also attended by former skipper Shaun Pollock and spinner Pat Symcox.
Klusener, who was axed from the national squad after South Africa bowed out in the first round of the 2003 Cricket World Cup, was recalled to the One-day International side during the New Zealand tour but was dropped for the Test series.
South Africa lost the One-day series and barely managed to draw the Test series against the Kiwis.
"Lance settled in pretty well in New Zealand. There's no doubt that South Africa is a poorer cricketing nation without him. Everyone seems to feel that he must be back in the side.
"Apart from his efforts on the field, he is contributing at team meetings - that in itself is a big change - because he used to keep quiet."
Donald, who retired from international cricket more than a year ago, said South Africa had missed Klusener in the Test matches.
"We will all love to see him back in Tests and One-day Internationals. Watching him bat in the Pro20 match the other night, it looked to me that he was back to his best with the bat.
"He is keeping his head very still as the bowler delivers the ball, which is a good sign. He is something pretty special," he said.
Kallis, who is seen as one of the top batsmen in the world today, paid tribute to Pollock for accepting with dignity his axing as captain.
"All credit to Shaun. He could have have turned nasty about the way he was fired, but he dealt with it very well. He re-dedicated himself to his cricket and worked just as hard as ever. You couldn't ask for a better team man."
Pollock, who was one of the most successful bowlers during the New Zealand tour, reacted to this by saying that his dream was to play for South Africa and not being captain.
"If I had turned grumpy, I would have undermined that dream," he said.