I am not asking here if Hashem Most High forgives you for a sin you committed, what I am asking is: is there anyway to know that Hashem has forgiven you for good so no matter what happens rest of your life, you will enter Olam Haba because you are forgiven. Are there any signs in your life or dreams you see that say that you are forgiven by Hashem Most Great?
Sefer HaYashar 9 (end):
אך אם יעשה דבר מצוה וישמח בה, ויחשוב כי כבר מצאה ידו, אף על פי שהיא נקלה, ואם יגע במצוה ההיא שמח מאד ביגיעתו ותמתק מאד לחכו, כאשר תמתק המנוחה לכסיל, זה לאות כי הבורא אוהב אותו. וכן בשמעו דברי אלהים, וייכנע לבבו, ויפחד מאד, ואף על פי שהוא רשע, יש תקוה לאחריתו שיחזור בתשובה, כי רוח היראה היא צפונה בלבו. ועל כן נדע, כי כשתחלש התאוה המעוורת עיניו או כשיבוא בימים, אז תתעורר לו היראה הצפונה בלבו, ועל כן הוא אות כי יש לבורא קצת אהבה בו. ועל זה יש לכל משכיל לשקול נפשו באלה המשקלים אשר זכרנו. ואם יכיר מהם כי הבורא מואס אותו, יזיל כנחל דמעה על רוע מזלו ואחריתו הרעה. ואם יכיר מהם, כי הבורא אוהבו, ישמח ויאמר, אשרי מה טוב חלקי ומה יפה גורלי. וימהר להעיר ולעורר את האהבה עד שתחפץ.
But when he fulfills a precept of the Torah and rejoices in it, because he was able to do it, even though the precept may have been an easy one to perform, or if he exerted himself in performing the precept and was very happy with the fact that he exerted himself, and it was very sweet to his palate, just as rest is sweet to the fool, this is a sign that the Creator loves him. Similarly, when he hears the words of God and subdues his heart and is very fearful and knows that he is a wicked man, there is hope for his final end, that he will repent, for the spirit of the fear of God is treasured up in his heart. Therefore, we know that when the lust which blinds the eyes grows weak, or when he reaches advanced age, then this fear which is hidden in his heart, will be stirred up, and, therefore, this is a sign that the Creator has at least a little love for him. Continuing with this theme, every intelligent man should weigh himself in these balances which we have called to mind. If he recognizes from them that the Creator rejects him, let his tears fall like a stream on the evil of his fate and on his sad end. If he discerns from them that the Creator loves him, let him rejoice and say, “Happy am I, how good is my portion and how beautiful is my lot,” and let him hasten to arouse and to stir up love to the extent to which he is able (Sefaria).
Nothing is guaranteed. However, we should not dwell on past deeds. The past is gone and we only need to pay attention to the lessons learned.
The Rambam said that people should progress and not focus on past sins and go on with their lives.
Judaism, unlike Christianitys’ presbyterian, does not promise grace after a verbal confession to G-d, but desires that we use our intelligence to improve the self. Since G-d does not interfere with natural law, it follows that it is impossible for a sign to materialize.
PS in Hebrew “sin” means Chet, which means “missing the mark.” Think of an archer shooting an arrow and missing his target. He should perfect his targeting. Not rely on G-d to forgive every action possible.