Is completing one's ablution without repeating it considered forbidden if involuntary thoughts occur during it?

The most important cure for whisperings (waswas) after seeking Allah's help is to ignore them and to defy what they call for. So, if the whisperings call you to rewash a limb or re-perform ablution, do not do it, as your ablution and prayer are valid. The most effective remedy is to cut off the path of these whisperings and to completely turn away from them, convincing oneself that this is the Sharia ruling by which one attains Allah's pleasure, and that indulging in them may expose a person to Allah's wrath. Scholars have mentioned that Satan has two instigations: extremism and negligence, and following the whisperings falls under the category of extremism.