Use Tinkerbell to fill up your power on level 1, then fly to the right and enter the cave filled with spikes. Carefully move through the cave until collecting a 3-up. Intentionally die and repeat this porcess to accumulate 99 lives.
Fall into the first chasm on the right at the beginning of level 5 the caves walk or fly to tinkerbell on the bottom of this area. A lfeaf will appear with a 3-up. Lose your current live and repeat this process to accumulate 99 lives.