Does repeating words of shirk, such as "Taha, the dispeller of distress," lead one out of the fold of Islam? And is merely abandoning them and criticizing the actions of the Sufis sufficient to return to true Islam, or is it obligatory to re-declare the Shahadah and perform ghusl?

Repeating polytheistic words, while knowing their error, can lead to apostasy. Thus, whoever commits an act of disbelief, knowing its prohibition but ignorant of its being an act of disbelief, is considered a disbeliever; because ignorance of the punishment is not an excuse, rather the excuse is ignorance of the ruling.

Mocking Allah, His verses, and His Messenger is an act of disbelief, and it indicates that they did not believe their action to be an act of disbelief, despite their knowledge of its prohibition.

Repentance from this involves ceasing the action, regretting it, uttering the two Shahadas, and performing ghusl (ritual bath) is more prudent to avoid disagreement.