Remove the my declaration and use vars to declare $var1 in your package and export $var1 and it will work.

use strict;
use lib ('.');
use MYPACKAGE qw / sub1 $var1 /;
use vars qw / $var1 /;
sub1();
$var1="PRINT THIS";
sub1();

package MYPACKAGE;

use Exporter;
use vars qw / @ISA @EXPORT @EXPORT_OK  /;
@ISA = qw/ Exporter /;
@EXPORT = ();
@EXPORT_OK = (qw/sub1 $var1/);;

use strict;
use vars '$var1';
$var1 = "DEFUALT I WANT TO CHANGE";
sub sub1 { print "var1 = $var1\n" }

1;

__DATA__
var1 = DEFUALT I WANT TO CHANGE
var1 = PRINT THIS
[download]

The OO way to do it is with get and set methods. The advantage of this is that a my var can not be accessed* outside the package so the only way to get/set the value is using the accessor methods. These can be useful as you can ensure that only valid values are set.

use strict;
use lib ('.');
use MYPACKAGE qw / set_var get_var/;

print  get_var(), "\n";
set_var('Some new val');
print  get_var(), "\n";

package MYPACKAGE;

use Exporter;
use vars qw / @ISA @EXPORT @EXPORT_OK  /;
@ISA = qw/ Exporter /;
@EXPORT = ();
@EXPORT_OK = (qw/set_var get_var/);;

use strict;
my $var1 = "DEFUALT I WANT TO CHANGE";
sub set_var { $var1 = shift }
sub get_var { return $var1 }

1;
[download]

cheers

tachyon

s&&rsenoyhcatreve&&&s&n.+t&"$'$`$\"$\&"&ee&&y&srve&&d&&print