On one hand, it is easy to give up on repentance. You recognize that some of your behavior is flawed and could use improvement. You call out to God but don't feel God answering. Even after you commit to change yourself, you find yourself slipping into your earlier behavior. You have a picture in mind of how you would like to see yourself, improved. But you see no clear path by which to get there.
On the other hand, it is easy to get the feeling that you had sins to atone for, but that now you regret them, will never repeat them, and in general have done the full measure of repentance. The yamim noraim require teshuva - but now you are close to God, you have done teshuva, and you are done with teshuva.
These are the dual challenges of the Yamim Noraim: to keep your heart up, but your head down. It's relatively easy to achieve one at the expense of the other, and whenever you work at one, the other tends to slip. It is extremely difficult to repent both out of love and out of fear. But that is the only way to achieve real character growth. Figure out in which of the two directions you are lacking. And work to bring yourself to the rigorous, painful, but morally productive emotional state in which you are vividly aware, both of the desperateness of your current condition, but also of the immense capabilities for love and growth that lie within you.