Is it necessary to repeat prayers upon waking up with wetness in the vagina, while assuming it is sweat and not a wet dream or madhy (pre-seminal fluid)?

As long as the situation is as described, you are not required to perform ghusl (ritual bath), nor do you need to repeat your prayers, as they are valid. The general principle is that what was, remains as it was. Therefore, if one doubts the invalidation of their wudu' (ablution) or the emission of mani (seminal fluid), they are not obligated to perform wudu' in the first case, nor ghusl in the second, unless they attain certainty. So, if you doubt the emission of anything, do not pay attention to the doubt and do not investigate. If you see something that could be mani or sweat, the default assumption is that mani has not been emitted, unless you are absolutely certain that mani, which necessitates ghusl, has been emitted. Only then are you required to perform ghusl al-janabah (ritual bath for major impurity). Beware of succumbing to obsessive thoughts (waswas).