You can with a step in between:
Code:
text= ; just for testing purpose using a variable here to show you how it works
(join`r`n
1
2
Maximum Stations: 4490
4
5
)
BosstaLine:=TF_Find(text,"","","Maximum Stations:",0,1)
RegExMatch(BosstaLine,"Maximum Stations: (\d+)",CurrentValue)
NewValue := CurrentValue1 - 1 ; note the 1 here see RegExMatch docs for info
Text:=TF_Replace(text,bosstaline,"Maximum Stations: " NewValue)
MsgBox % CurrentValue1 "---" Text
/* for your file it would become:
BosstaLine:=tf_find("Daily Check subtraction.txt","","","Maximum Stations:",0,1)
RegExMatch(bosstaline,"Maximum Stations: (\d+)",CurrentValue)
NewValue := CurrentValue1 - 1
TF_Replace("!Daily Check subtraction.txt",bosstaline,"Maximum Stations: " NewValue)