Is it necessary to wash the body and clothes, or is it sufficient to sprinkle water on them when madhy (pre-seminal fluid) is discharged involuntarily on a daily basis?

If it is merely a matter of whispers (waswās), then pay no attention to them, and you are not required to perform ghusl (full ablution) or nadeh (sprinkling). However, if you are certain of the emission of madhi (pre-seminal fluid), which is impure (najis), then it is obligatory to purify whatever parts of the body and clothing it has touched before intending to pray. The body is purified by pouring water over the defiled area until the impurity is removed. As for clothing, it suffices to sprinkle water on the area affected by madhi, and this is the more preponderant opinion. What you are doing by washing the body and sprinkling the clothes is what is religiously obligatory.