Synonym for "increase by one" for use in technical publication

I was wondering if there is a synonym for the word group "increase by one". Example:

"If the shoe didn't fit, the shoe size was increased by one size."

I think it sounds weird because of the repetition of "size", however, I think I cannot just delete the second "size". So I thought there might be a synonym to give the sentence more variability.

Or does the sentence below sound natural to native speakers?

"If the shoe didn't fit, the shoe size was increased by one."

P.S.: The intended use is a technical publication, so please no colloquial terms or phrases.

P.P.S.: For the offended footlocker headquarter - imagine a series of tubes in your kitchen that come in sizes one, two, three (I hear already plumbers shouting "no, they don't") and the same situation "If the tube was too small to connect with the sink, the tube size was increased by one."

Yup, I got it now, you could say "the next size was chosen" and I will never ask a question here again because obviously this here is native speaker corner and these kind of synonym questions are trivial. So long, and thanks for all the fish.

Solution 1:

Increment, according to Merriam Webster:

the action or process of increasing especially in quantity or value

In programming this is often used to add one, for example in a loop. In your shoe example you are essentially doing the same, you start with some size and increase by one until it fits.

The opposite, if the shoe is too large, is called decrement. You start with some shoe size and try smaller ones until it fits.

Solution 2:

"Increase by one" is perfectly fine. No need to depart from normal (and in this case precise) English in technical documents. You don't need a fancy word. If you're indeed talking about something abstract, then yes, "increment" might be better but if you don't know that's the right answer it's probably not the right answer.