Theory:

Diacope is a kind of repetition where the repeated words will have a word or few in between them.
Pronunciation Guide:
Diacope: Dia (as is Diana)-- co (as in code)-- pe (as in pin)
This kind of repetition is similar to epizeuxis. The difference is that: there is no break given to the repeated words in epizeuxis; but, on the other hand, the repeated words are separated by one or two words in the case of diacope.
 
Let us have some examples now!
 
The following is an extract from the poem "Fear No More" by William Shakespeare.
Example:
Fear no more the lightning-flash,
Nor the all-dreaded thunder-stone;
Fear not slander, censure rash;
Thou hast finished joy and moan:
All lovers young, all lovers must
Consign to thee, and come to dust.
In the poem, the phrase "all lovers" are repeated but with the word "young" in between them. So, the word young has separated the repeated words "all young". Without the words in between, the repetition would have become epizeuxis. However, due to the break, the repetition become diacope!
 
The following is an extract from Rabindranath Tagore's "Vocation".
Example:
When the gong sounds ten in the morning and
I walk to school by our lane,
Every day I meet the hawker crying,
Bangles, crystal bangles!”
The line "Bangles, crystal bangles" is an example of diacope. The word crystal has separated the repeated words bangles.
In diacope, the repeated words could be separated by more than one word. Sentences such as "I have it and I will not give it to you", "to be, or not to be", "she is a doctora sweet and compassionate doctor" are examples of diacope. In the above-given sentences, the number of words between the repeated words vary. There were \(3\) words in the first sentence, \(2\) words in the second sentence, and \(4\) in the third sentence. 
Diacope used in the poem "Macavity: The Mystery Cat":
Macavity’s a Mystery Cat: he’s called the Hidden Paw —
For he’s the master criminal who can defy the Law.
He’s the bafflement of Scotland Yard, the Flying Squad’s despair:
For when they reach the scene of crime — Macavity’s not there!
 
Macavity, Macavity, there’s no one like Macavity,
He’s broken every human law, he breaks the law of gravity
.
His powers of levitation would make a fakir stare,
And when you reach the scene of crime — Macavity’s not there!
You may seek him in the basement, you may look up in the air —
But I tell you once and once again, Macavity’s not there!
 
Macavity’s a ginger cat, he’s very tall and thin;
You would know him if you saw him, for his eyes are sunken in.
His brow is deeply lined with thought, his head is highly domed;
His coat is dusty from neglect, his whiskers are uncombed.
He sways his head from side to side, with movements like a snake;
And when you think he’s half asleep, he’s always wide awake.
 
Macavity, Macavity, there’s no one like Macavity,
For he’s a fiend in feline shape, a monster of depravity.
You may meet him in a by-street, you may see him in the square —
But when a crime’s discovered, then Macavity’s not there!
The lines/phrases "Macavity, there’s no one like Macavity", "once and once ", and "side to side" are examples of diacope.
    Reference:
  • National Council of Educational Research and Training (2006). Beehive. Fear No More-William Shakespeare (pp. 137). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.
  • National Council of Educational Research and Training (2006). Honeysuckle. Vocation-Rabindranath Tagore (pp. 109). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.
  • National Council of Educational Research and Training (2007). Honeycomb. The Shed: Frank Flynn (pp. 48 -49). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.