Must I repeat the prayers I performed after I found a fluid resembling maniyy and doubted my puberty at that time?

The emission of semen is one of the signs of puberty, if it is confirmed. However, if there is doubt as to whether what was emitted is semen or not, then puberty is not established by it, nor is ghusl (definition) (ritual bath) obligatory from it, due to the lack of certainty regarding its cause. This is because puberty is not established by doubt. Therefore, if you have no other signs of puberty except this doubtful one, you are not considered to have reached puberty and are not required to make up the prayers you performed without ghusl.