What penance or the like is incumbent upon me after supplicating against myself for failure in exams, in order to refrain from watching TV series and reading novels? And will this supplication be answered?

The response of a supplication against oneself is a matter of the Unseen, known only to Allah, and no expiation is required merely for supplicating against oneself. It is advised to refrain from supplicating against oneself, one's children, and one's wealth, lest it coincide with a time of acceptance (of supplication). It is also advised to avoid watching television series, as they often contain objectionable content.