The possuk says that the Malachim were עלים וירדים בו. Rashi points out that first they were going up and then going down. I think Rashi is giving a mesage of chizzuk. In order to fall one must go up first. So if you do fall know that there must have been an aliyah first. Rather than focus on the fall, focus on the fact that you had an aliyah.
Another thing. Both עלים and וירדים are spelled choser without a vav. This is for those who strive for perfection. First, even the molochim don't have perfect aliyahs, so don't kick yourself when your aliyah is not perfect either. And if you do fall, know too that there is no such thing as a perfect fall. There is often some redeeming factor that can be found and while it may be unfortunate that there was a fall, there is something to take out of it to help you grow, so that even the downs in life are a means to go up.
The possuk says כי, לא אעזבך, עד אשר אם-עשיתי, את אשר-דברתי לך Rashi on the words לך says that means על since this was the first time that Hashem had spoken with Yaakov. If you think about this, Yaakov was 77 years old at the time, he spent the last 14 years learning day and night without sleep and yet this is the first time Hashem is speaking to him. We often think that oh we've been clean for x amount of time (like three days or even three years), and things are still looking glum, my life hasn't turned around, does Hashem love me? How much does he want from me? If we would expect Hashem to show his presence to anyone it would be Yaakov, yet the RBSO did not appear to him right away. But know that even if you don't see "Hashem" in your daily lives, Hashem says "אנכי עמך."