Something like this should do the trick.
First line value to match on 1 replacement value @2
Second line value to match on 2 replacement value @3
Continue this pattern as high as you need to. No regex needed for these.
Then on the very last line do value to match on @ replacement value -BLANK- with regex turned on to remove the @ symbols and leave only the needed numeric value.
Brilliant - thanks John.
Using a regular expression, is there a way to replace a numeric value with a number that is 1 higher? So replace 1 with 2, 2 with 3, 3 with 4, etc.