The shrine, which features a four-faced golden statue of the Hindu god Brahma, was damaged in at least 12 places.
It is considered sacred by Thai Buddhists and attracts many foreign visitors.
At its opening ceremony, culture minister Vira Rojpojchanarat said the statue would help "create confidence and raise the morale of Thai people and tourists".
Visitors have continued to visit the shrine since it reopened shortly after the bomb blast on August 17.
Two people have now been detained in connection with the attack. No individual or group has yet claim responsibility for it.