You might also try, especially if "Some Text 1:" isn't standardized and you don't actually want the word "Data":

$str= "Some text1 : Data Some Text2";
$str=~/:\s+Data\s(.+)\z/;
$youwant=$1;             ##$1 is the captured (.+) part
print $youwant;
[download]

prints "Some Text2"

It's not technically a substitution, of course -- $str remains the same -- but if you wanted to you could just set $str to $youwant at the end (or even to $1 earlier). or you could:

$str= "Some text1 : Data Some Text2";
$str=~s/.+?:\s+Data\s(.+)\z/$1/;
print $str;
[download]

to use the substitution operator.. .

update: I thought the "Some Text2" WAS the data, and the "Data" was a literal (I don't know, announcing that a bunch of data was to follow, or something. Dense of me, I guess). My suggestions could be modified, but it would depend on what "Data" contained.

update2: dani_cv_72 looks quite a bit like dani_cv_perl, who posed very similar questions.