use strict;
my $str = '"symbol": "ETHBTC",
"filterType": "LOT_SIZE",
"minQty": "0.00100000",
"maxQty": "100000.00000000",
"stepSize": "0.00100000"
"minQty": "0.00000000",
"maxQty": "9201.00570633",
"stepSize": "0.00000000"
"symbol": "LTCBTC",
"filterType": "LOT_SIZE",
"minQty": "0.01000000",
"maxQty": "100000.00000000",
"stepSize": "0.01000000"
"minQty": "0.00000000",
"maxQty": "33144.83294363",
"stepSize": "0.00000000"';
my $regex = qr/("filterType":\h+"LOT_SIZE",(?:\R\h+"[^"]+":\h+"[^"]+",?){3})(?:\R\h+"[^"]+":\h+"[^"]+",?){3}/mp;
my $subst = '$1';
my $result = $str =~ s/$regex/$subst/rg;
print "The result of the substitution is' $result\n";
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html