I've written, last year and already this term, on the matter of repetition. Repetition as a key to matters of both form and invention (or, what we make as well as how we make it: product and process) is an obsession of mine -- because it is both simple and complex as a concept.
So, I try to approach it in different ways. Technology (online tools, that is) allows some new approaches, although they resemble skills that are already necessary to reading and writing.
For example, the simple CTRL + F command (in your browser or in Word), which allows you to quickly locate instances of a word or phrase. Take a text of your own, or of any writer, and search it for various words and word-patterns: what do you notice of primary terms, instances of repetition, proximity of certain words, etc.?
Another useful tool is a tag cloud. A cloud allows you to create a visual representation of word occurrences.
Before proposing an experiment, I will develop my thoughts a bit more. Creativity is, from one angle, a matter of finding associations that others don't notice, or that are in some way volatile -- leading to further associations, for one thing. Art is pattern-making; repetition is the tick-tock of pattern-making and pattern-recognition. Between two things, including two instances of the "same" thing, there are many dynamics: a matrix or space of possible value or meaning, a tonality derived from the combination of the two things, a sense of speed in traveling between the two, a texture, a rise, a fall, etc. (Tick-tock: what is that vocable we use for naming time except the resistance to seeing a second instance of the same thing as the same thing? We have to alter it; we have to invent the illusion of change.)
Writers develop their works, they invent and discover, partly through returning to a point of observation, obsession, desire, fear, or memory. Language allows us to see many in one: Love is love, but it is also lust, ardor, passion, longing, romance, fondness, amorousness, and many other "synonyms" that are really different angles, different degrees, different stages, different influences, different steps on different ladders of experience. Also, each word, each concept or node of experience, has it's opposites: hate, loathing (an almost-rhyme with loving!), despising, disliking, detesting. One word, one node, when touched, reveals many possible pathways forward. We fit experience to language, and language to experience. We invent, and yet we re-inhabit forms that writers have always used; we speak words and phrases, perform entire conversations, that others have had before us. Life is a ritual, life is a discovery -- both.
One way to think of art-making is as a way to move forward (to discover, to escape, to survive) and at the same time stay still (to preserve, to persist). This is a paradox -- a puzzle that making art seems to undo, but really it adds other layers to the puzzle. Repetition, creating of patterns, invention of form -- these are ways we engage the paradox.
This is all rather abstract and high-falutin', I know. It is a felt notion more than a theory, I guess. So, let me push into the experiment, and see if you have any insights of your own -- ways to make more concrete and practical my ethereal ramblings:
Look at these two texts by classic American authors -- Ralph Waldo Emerson, "Nature" and T.S. Eliot, "The Love Song of J. Alfred Prufrock." Emerson's text is a long essay, Eliot's is a longish poem; the essay is from the early 19th century, the poem from the early 20th century. Both use reiterations of words and concepts. What I'd like you to do is to use CTRL + F, and/or simply your own scanning/re-reading/note-taking skills to study how the writers use repetition at the word/phrase level. Specifically, for Emerson -- focusing mainly on the Intro and Chapter 1 -- how often does he use words that have to do with SEEING an LIGHT? Don't look only for those words; think about what words are in some "family resemblance" with them: words that directly or indirectly have to do with seeing, light, and their opposites.
Then, in Eliot's poem, discover how often he repeats the same words, but also, again, consider how those words form patterns in association. Study as well how those clusters of similarity change and move in the poem.
Finally, for fun, copy and paste some or all of the texts -- and any other text -- into this resource, "Wordie" -- a word-cloud generator. What words are dominant? What forms do you see in the hierarchies of repetition?
As a final "Exercise," you might take the most frequently used words and write your own story/essay/poem with them.