You might be able to use Win32::Process.

Here is an example of finding a process (Notepad) by executable name then monitoring it and taking action when it terminates:

use strict;
use warnings;
use Data::Dumper::Concise;
use Win32::Process::List;
use Win32::Process;

my $p = Win32::Process::List->new();
my %list = $p->GetProcesses();
foreach my $pid (keys %list) {
    if($list{$pid} eq 'notepad.exe') {
        my ($obj, $iflags);
        Win32::Process::Open($obj, $pid, $iflags)
            or die "Win32::Process::Open failed";
        $obj->Wait(INFINITE);
        print "Done waiting\n";
        exit(0);
    }
}
print "Notepad process not found\n";
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And here is an example of starting Notepad from Perl, and restarting it when it exits:

use strict;
use warnings;
use Data::Dumper::Concise;
use Win32::Process;

my $obj;
while(1) {
    Win32::Process::Create($obj,
        "C:\\windows\\system32\\notepad.exe",
        "notepad",
        0,
        NORMAL_PRIORITY_CLASS,
        ".") or die "Failed to start notepad";

    $obj->Wait(INFINITE);
    print "Notepad exited - restarting\n";
}
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If you want to do something while the process continues to run, you can do that too:

use strict;
use warnings;
use Data::Dumper::Concise;
use Win32::Process;

my $obj;

while(1) {
    Win32::Process::Create($obj,
        "C:\\windows\\system32\\notepad.exe",
        "notepad",
        0,
        NORMAL_PRIORITY_CLASS,
        ".") or die "Failed to start notepad";

    while(1) {
        $obj->Wait(10000);
        my $exit_code;
        $obj->GetExitCode($exit_code);
        if($exit_code == Win32::Process::STILL_ACTIVE()) {
            print localtime() . ": Do something while notepad runs\n";
        } else {
            print localtime() . ": Do something when notepad terminate
+s\n";
            last;
        }
    }
}
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