I run into this often enough myself. My preferred way to handle it is manually with some slightly advance search and replace techniques.
In this case, since you are going to be changing the last character of the block, and you can visually see what you want to work on, I might do the following:
This will search for the target text and put your cursor at the end (the 1) which is what you want to change. Then I would do the following keystrokes in normal mode
r4 # replace the 1 with a 4
n # goes to the next match, places you at the end
. # does the same substitution of 1 to 4
# repeat n and . until you've finished the block for 4
When you get to the next block where you want a 5, just do a
r5 and then
You then are just bouncing between the 'n' and '.' and if you go too far, you can just use 'u' to undo. Very fast and limited typing is required.