Is there a supplication or any way to restore sincerity in the heart and commitment to prayer, after feeling the presence of attributes of hypocrisy and a lack of sincerity as before?

You must repent, frequently seek Allah's forgiveness (istighfar), and maintain all prayers, as abandoning them is a great calamity and one of the gravest major sins. Things that will help you with this include: keeping good company, paying attention to prayer times, hastening to pray immediately upon the adhan, believing firmly that prayer is the greatest pillar of Islam after the two testimonies of faith, increasing in acts of obedience, distancing yourself from bad environments, evil deeds, and immoralities, striving diligently in your actions while making supplication. There is no specific supplication prescribed for maintaining prayer, but you can supplicate with what was mentioned in the question, and increase in reciting the Holy Quran, making supplications, and seeking forgiveness.