Is it permissible to continue plucking and applying kohl to the eyebrows after repentance, and is wiping only the lower part of the face during ablution valid in this case?

You, O questioner, must fear Allah and perform ablution and prayer as Allah has commanded you. Your wiping of your face does not validate your ablution or prayer, and you must make up all the prayers you performed with such ablution. You must also avoid imitating women. Furthermore, shaving the eyebrows falls under the category of namṣ (plucking or thinning eyebrows), for which the Messenger of Allah, peace and blessings be upon him, cursed the one who does it, whether it be by plucking, trimming, or shaving.