Have you started hating the sin for which you repented? If yes then that is the sign of acceptance of your repentance.
(Sometimes a whispering comes to the heart of us dirty people in response to above type of answers. "What kind of answer is that?", it says. "Isn't that obvious?", it adds. "Can't there be a more tangible sign?", the whispering insists. If someone would demand specification of tangible signs then the answer might be, "Like falling of flowers from the sky or something like that." This whispering could be Satanic but it is more probably our baser self. Qari Amir Hasan Sahab (DB) calls it our biggest enemy. Above whispering is a result of our tuning with the materialistic and ignoring the spiritual. Appearance of hatred for an action, the sin, for which we had, so to say affection, is no less tangible than a physical object.
So if we start hating a sin towards which we were at least oblivious then that is a blessed moment. We have had a transaction with our Lord Almighty and that is no insignificant matter. Only if we could appreciate it!)
(An earlier sitting (majlis))