Store the guesses in a hash: 
use warnings;
use strict;

my %guesses;
my $program_guess = int(rand 10)+1;
while (1) 
{
    print "Please give a number between 1 and 10\n";
    my $user_guess = <STDIN>;
       chomp $user_guess;
    if (exists $guesses{$user_guess}) {
        print "The number you guessed is a repeat, please try again!\n
+";
        next;    
    }
    else {
        $guesses{$user_guess}++;
    }

    if ($user_guess > $program_guess)
    {
        print "The number you guessed is higher, please try again!\n";
        next;
    }

    elsif ($user_guess < $program_guess)
    {
        print "The number you guessed is lower, please try again!\n";
        next;
    }

    print "You got the correct number!\n";
    last;
}

[download]

In reply to Re: Adding one last conditional in a random-number guessing game by toolic
in thread Adding one last conditional in a random-number guessing game by Anonymous Monk

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