The are many ways to interpret the two "Little Girl" poems in Songs of Experience. Following Raine I have focused on the neoPlatonic viewpoint:
Little Girl Lost

In futurity I prophesy
That the earth from sleep
(Grave the sentence deep)
Shall arise, and seek
For her Maker meek;
And the desert wild [this mortal world]
Become a garden mild.

Here in Blake's inimitable poetry we have the biblical New Heaven and New Earth. It is also a promise of the happy outcome of Blake's myth. (Look at Jerusalem, plates 96-99.)

*****************
In the southern clime, [the eternal realm]
Where the summer's prime
Never fades away,
Lovely Lyca lay.

Seven summers old
Lovely Lyca told.
She had wandered long,
Hearing wild birds' song.

'Sweet sleep, come to me,
Underneath this tree; [the Elm of Hades]
Do father, mother, weep? [like Demeter wept.]
Where can Lyca sleep?

'Lost in desert wild
Is your little child.
How can Lyca sleep
If her mother weep?

'If her heart does ache,
Then let Lyca wake;
If my mother sleep,
Lyca shall not weep.

'Frowning, frowning night,
O'er this desert bright
Let thy moon arise,
While I close my eyes.'

Sleeping Lyca lay,
While the beasts of prey,
Come from caverns deep,
Viewed the maid asleep.

The kingly lion stood, [lion=Pluto, king of the underworld]
And the virgin viewed:
Then he gambolled round
O'er the hallowed ground.

Leopards, tigers, play
Round her as she lay;
While the lion old
Bowed his mane of gold,

And her bosom lick,
And upon her neck,
From his eyes of flame,
Ruby tears there came; [Why was the lion sorrowful? Did he mourn the descent of the soul?]

While the lioness [the lioness?]
Loosed her slender dress,
And naked they conveyed
To caves the sleeping maid.

Little Girl Found

All the night in woe
Lyca's parents go
Over valleys deep,
While the deserts weep.

Tired and woe-begone,
Hoarse with making moan,
Arm in arm, seven days
They traced the desert ways.

Seven nights they sleep
Among shadows deep,
And dream they see their child
Starved in desert wild.

Pale through pathless ways
The fancied image strays,
Famished, weeping, weak,
With hollow piteous shriek.

Rising from unrest,
The trembling woman pressed
With feet of weary woe;
She could no further go.

In his arms he bore
Her, armed with sorrow sore;
Till before their way
A couching lion lay.

Turning back was vain:
Soon his heavy mane
Bore them to the ground,
Then he stalked around,
Smelling to his prey;
But their fears allay
When he licks their hands,
And silent by them stands.

They look upon his eyes,
Filled with deep surprise;
And wondering behold
A spirit armed in gold.

On his head a crown,
On his shoulders down
Flowed his golden hair.
Gone was all their care.

'Follow me,' he said;
'Weep not for the maid;
In my palace deep,
Lyca lies asleep.'

Then they followed
Where the vision led,
And saw their sleeping child
Among tigers wild.

To this day they dwell
In a lonely dell,
Nor fear the wolvish howl
Nor the lion's growl.