There are two sets of floating rocks that must be jumped across in the Sand People level. At the very beginning of the second set of rocks, jump off the edge of the cliff and face to the left. Luke will land on a ledge and enter a small cave area. Ignore the falling rocks and shoot the blaster in the air to reveal several extra lives. Collect them and lose your current life to restart the level at the top of the cliff. Repeat this procedure to collect up to ninety-nine lives.