Hey Jeannie,

I know this is an older post, but I thought I would try to add my experience which may help for future visitors if nothing else.

I too have had similar experiences and most of the time what I can pick out are subtle changes in the music for each verse that help me recognize when the lines should be different. I learn to associate the lines with that little nuance(s).

I do not write music, but if I did, I would think it would certainly be something useful to be able to add.
For example in your first two verses

Hush-a-bye my little baby,
Night will soon be here.
Sandman's comin' so close thine eyes
And sleep my little dear.

~maybe add a bit of a flute solo (disclaimer - I do not play nor do I have an affliction for flutes, I simply think of wind instruments when I think of lull-a-byes, I also have not heard your music for this piece, so I am not sure that a flute would work, just a suggestion... wow, maybe I should be a politician. LOL!)
or simply change one or two notes in the break or at the end of each repetitive line.

Hush-a-bye my little baby,
Dreamland's drawing nigh.
Angels guard thy little bed,
Watching from the sky.

Without hearing the melody for the song, it is difficult to make specific suggestions, but I hope you catch my drift.

Also, something I have not used, but will try in the future... add an "invisible" word to the end of each repetitive line. One that you see/hear mentally when you are singing, but do not actually vocalize. This may be more confusing than it is worth, but I would speculate is at least worth a try. I would even go as far as making it something that would rhyme with the 2nd line last or first word to trigger the memory of the next line.
ie:
Hush-a-bye my little baby(dear/near/fear),
Night will soon be here.
Sandman's comin' so close thine eyes
And sleep my little dear.

Hush-a-bye my little baby (bye),
Dreamland's drawing nigh.
Angels guard thy little bed,
Watching from the sky.

To me, it is almost like an epiphany. When I discover what works, it just clicks.

I hope this is helpful!
Have a great day!

I want to write music that I can ultimately sing. \:\)

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