You can use something like:
$t->waitfor( Match => '/FLMON>/', Timeout => 120 );
to look for the prompt. This is particularly handy if the prompt changes through the process.

Else if the prompt remains static, you can set the prompt permanently like this:

$t = new Net::Telnet (Timeout => 10, Prompt => '/bash\$ $/');
[download]

Obviously, http://search.cpan.org/~jrogers/Net-Telnet-3.03/lib/Net/Telnet.pm is place to look for more details.

Hope that helps.
Lance