What is the ruling on the prayers I performed while my underwear was contaminated with drops of urine due to my remaining for a long time without using the restroom, knowing that I thought I had urinary incontinence, and sometimes I would only wash the contaminated area, and at other times I would take off my underwear for prayer? Do I have to repeat the prayers of those years?

If the discharge of urine is merely an illusion, then do not pay attention to it, and there is no need to change or wash the clothes. If you are certain that something has been discharged, then only the soiled area should be washed with water, and there is no need to change the clothes. Praying in a single garment is valid if it covers the 'awrah. If the discharge of urine is continuous, then you are considered to have incontinence (sals). If you were unaware of any of the conditions for prayer in the past issues, then, according to Ibn Taymiyyah, there is no need to repeat the prayers. Furthermore, according to the Malikis, there is no need to purify oneself from these drops.