I was going to head back into the Soul Cairn, to find Serana's mother again and just for fun really, but I can't seem to take the portal through. I have tried everything from dropping Auriel's Bow and the Sunhallowed arrows from my inventory, to becoming a VL from Serana but all that seems to happen is that I lose health from it.

Is there actually any way for me to re-enter the Soul Cairn if I've completed the Dawnguard side of the story?

How did you enter the first time?
Did you let Serana trap your soul?
Or were you a Vampire then?

If she trapped your soul...Did you get it back?

I let her turn me into a vampire first time.

Then you have to be undead (i.e. a Vampire) to get back in.

If you let her Soul Trap you on the First Trip, then as long as you retrieved your Soul Gem you would've been able to enter it whenever you wished.

But for now, you have to be undead to enter the Realm of the Undead in Oblivion.

Like I said in my OP, I tried being a Vampire Lord but it still didn't work.

Well, OP...I am at a loss, my friend. You must Fast travel to the Balcony, to start with.

Do you have a previous save "before" you FT's there and realized you could not enter?

Reverting to a previous save and letting her turn you before you tried to reenter may reset the mechanics. If you just leave, get turned and THEN return, it could be set to a glitch.

I've not got a save before it, so I guess I'm stuck with it. Haha.

Thank you very much for the help though, I appreciate it.

Do you have Serana with you?

Having her there while you are still in human form, may open the dialog option from her again.

I do have her, but she says nothing about soul trapping me and I've already tried making her turn me into a Vampire Lord with no success.

Hey buddy, what must i do as a mortal soul to keep visiting the soul cairn? i just went in so i still can... i don't know if i got my soul back, but i did something with a black soul there... don't know if that means i got it back or not.

Valerica says i'm attuned to it... no difficulty using the portal she says.

Does that mean i have my soul back or not?

Edit: how DO you get your soul back anyway?

Sorry guys. I am at a total loss with this. Thus I am completely worthless in giving any advise what so ever as I have yet to explore the "Soul Gem" option of entering the Soul Carin.