The Return Of The Yaakov

In last week's parsha we learnt that Yaakov called Luz Bais Kel (28:19) so I don't understand why in this week's parsha (35:6) the Torah remindes us that Luz = Beis Kel and furthermore, the Torah says in verse 7 that Yaakov called it Kel Beis Kel and he erected a mizbaoch there.  Why did he erect a mizbaoch if in last week's parsha he already erected a matzevah?  And why the new renaming ceremony?  The Rashbam says last week's parsha was dealing with the city itself and Yaakov called it Beis Kel.  Here he is outside the city and is calling it Kel Beis Kel.  The Or Hachaim understands its the same place but now Yaakov decided to call it Kel Beis Kel for Hashem indicating Hashem didn't just appear to him there but shall constantly rest His Presence there.  Based upon the Or Hachaim we can understand that the Torah repeats the name was Luz for yes, Yaakov had transformed it to Beis Kel, but it didn't make a permanent impression.  When Yaakov left Eretz Yisroel he called it Beis Kel so that Hashem should protect him on his journey.  It marked his point of departure from kedusha into another world but after his short stay the kedusha vanished.  As he is returning, he will make it a permanent place of kedusha, hence the new name, Kel Beis Kel.  It is the return of Yaakov, not as a single man, but as Yisroel, a nation that will bring kedusha to the land they tread upon.  As to why the mizbaoch instead of matzevah,  I would suggest that we know from Rashi (Shoftim 16:22) that a matzevah is one stone as opposed to a mizbaoch which is many.  Only after Yaakov has given birth to the shevatim, Klal Yisroel, is there a merging of numerous talents together.  Previously each Av found his niche in one path of the service of God, it only with the formation of tribes with unique traits and qualities that there is a merger represented by the many stones coming together.