What is the ruling on a female getting a second piercing of her ear? The piercing will be on the lobe, but next to the first on.

Praise be to Allah, the Lord of the Worlds; and blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

There is no harm for a female to get her ears pierced as many times as needed, provided the operation is safe. However, the following conditions should be met.
1. She should cover her ear from all men except the categories mentioned in the following verse:
{….. and not to reveal their adornment except to their husbands, their fathers, their husband's fathers, their sons, their husband's sons, their brothers or their brother's sons, or their sister's sons, or their (Muslim) women (i.e. their sisters in Islâm), or the (female) slaves whom their right hands possess, or old male servants who lack vigour, or small children who have no sense of feminine sex.}[24:31]
2. There should not be any imitation of the non-Muslim women.
3. The thing put in the ear should not be a cross or any other symbol of non-believers.
On the other hand, it is unlawful according to Sharia, for the man to get his ear pierced as doing so is an imitation of the non-believers.
The Prophet cursed men who imitate women as reported by Al Bukhari in a sound Hadith. If the man puts some golden ornament in his ears he commits several sins at the same time:
1. Imitating women.
2. Imitating dissolute non-believers.
3. Wearing golden-made things if the ornament is from gold.
Allah knows best.