Post exploitation : exploiting other windows 7 machines within the network

In Metasploit lets say i have pivoted a win 7 PC by some triggering exploit. And i exploited a win XP machine within say using smb/ms08_067_netapi but that's only with XP machines, i tried exploit another win 7 PC from my pivoted machine by uploading a meterpreter shell but exploit failed. My question is after pivoting a win 7 machine how can we exploit another machine with Win 7,8 (Not XP) by uploading a meterpreter shell without having a physical access to that machine.