For Move, the Strength Upgrades don't say they can be triggered multiple times, while the Range and Magnitude Upgrades do; would be rather silly to include a sentence that specifically says "you can activate this Upgrade multiple times" if the general assumption was that all Upgrades could be activated more than once.
Simple. It's an example and reminder. Maybe you're more likely to use Range or Mag multiple times than Strength, but there is no reason why it can't be used. This can also easily be explained away as a simple copy-paste or formatting error rather than a specific omission, since this is the only instance of this omission (not exception) in EoE.
Page 278, second column, second last paragraph, last sentence. "Unless specified otherwise, each ability may be activated multiple times." Futhermore, the sentences in the upgrades are a reminder about a rule, not a rule in and of itself.
What's more important in the Move example is that the passage doesn't specify that it cannot be used, as per the rule on page 278. As I mentioned, it's an umbrella rule that is only trumped if another rules specifically trumps it. Because strength upgrades do not specifically spell out that it can't be used multiple times (vs. non-ranked talents or the effects of certain ranked one specifically saying that it doesn't stack), the umbrella rule is the most appropriate one.
Now, this would only apply to "paid" upgrades that can be applied multiple times. The control upgrade for Influence that lets you make a Power check as a part of your skill pool, for example, couldn't be doubled up. You are already adding Force dice as a part of your pool. You can't add the dice as a part of your pool again. Likewise, the power's strength upgrade increases the strain inflicted to 2 from 1. You can't increase it to 2 twice.
As a functioning example of this form the movies, Luke was able to briefly move his X-Wing, but ended up failing. Perhaps he was missing the right number of upgrades, and instead used the upgrade multiple times. He failed because he couldn't generate enough points for the effect. Something similar is seen when Vader is able to detect Obi-Wan at planetary range in New Hope, and when Luke is able to do the same with Vader when aboard Shuttle Tyderium in Jedi, even though the ranges would be too far away for any power detailed thus far.
But again, no Force user in EoE or AoR is going to have enough dice to roll in order to be activating more than one or two upgrades more than once. So while it is hilariously easy to, say, use Move to push a Star Destroyer at planetary range, it's not an effect that can easily be created with the current limits on Force rating and dice pools.