Is the prescribed manner of ghusl sufficient despite forgetting to mention the intention before ghusl, and is it obligatory to send the manner for review again?

If the person performing ghusl (ritual bath) restricts themselves to the intention and covers the entire body with water, that is sufficient, and the state of janaba (ritual impurity requiring ghusl) is lifted from them. However, if someone does not intend to lift the state of janaba, their ghusl is not sufficient, and the janaba is not lifted from them; this is based on the Prophet Muhammad's (peace be upon him) saying: "Deeds are only by intentions." One must be careful of waswas (obsessive whispering/doubt) and not follow it.