1, Your bass may have been made with Hide glue and not white or yellow glue. First mistake I think!
2, Your bass may have a dove tail joint and not a mortise so what you see is the fit of the dovetail's slop as it has come loose. Again, Hide glue.
3, Before fixing string instruments (played with a bow) as opposed to stringED instruments (stringED means the other ones with strings, not bowed), you should learn about it's construction before you start doing repairs that will be harder to un-do than be done in the first place if repaired with the correct glue.
What looks easy now is what nightmares are made of when these come in for repair at real Bass Luthiers shops.
There are a few guys that specialize in Plywood basses and their repairs.
http://kaybassrepair.com/
http://www.fretwellbass.com/
These are two of them and I know there is one more, maybe listed on the first website as well.
The best thing is to learn from people that know before using glues that can't be undone without making a mess and making the job bigger than it was to begin with.
I am sure once you learn what exactly to do, you will see that it is best to do it right the first time. What you have done with the laminations, if and when THEY come apart as you have now mixed two kind of glues in there (the original and the new mix), that re-doing it again will be a royal pain.
The neck repair is a big and important job. It would be advisable to learn more before you try doing it yourself.