If you need to do this often or if that value is a parameter/variable that is common to a bunch of formulas, perhaps that value should be a cell reference vs hard coded into the formulas. This might be a good time to make that change.
As a general statement, it would not be a simple thing for the app to automatically update all the other non-identical formulas based on the change made to one formula, nor would you want that to happen usually.
Formula A = C2*5
Formula B = (C2-5)*5
If you change the "5" to a "6" in formula A, do both 5's get changed in formula B or just one (and which one) or do you not want it to change formula B at all?
But if cell D2=5 and
Formula A =C2*D2
Formula B =(C2-D2)*5
then it would "update all the formulas" whenever you change the value in cell D2.
To your question ,though, I cannot think of an easy way to update a number in a bunch of dissimilar formulas, except one at a time. I thought about using the FORMULATEXT formula in a new column, then copy / paste formula results to turn them into actual text, then find/replace to change the value in each, but then you have to copy/paste each "formula" one-by-one back to its matching cell to overwrite the old formula. Unless there are a lot of them, this entire procedure is just as much work.
It might be possible to do something with Applescript but I feel the time it would take to write and test the script would be longer than the time it takes to do it manually.