What is the way to regain a deep sense of remorse for missing prayers and falling short in acts of worship, and how can devotion and joy in prayer be achieved to avoid missing them?

Your feeling of distress and pain is the regret required for the validity of repentance. Continue on the path of righteousness, and strive in obedience to Allah the Almighty by observing the obligatory duties, avoiding prohibitions, and increasing in supererogatory acts. If a sin occurs, do not despair or lose hope, for the door of repentance is open and "the one who repents from sin is like one who has no sin." Beware of neglecting prayer, and if you wish to sleep after its time has begun, take measures to wake up before its time expires, and it is not permissible for you to sleep if you predominantly believe that the prayer time will pass.