Original Console2 - can't do that you want.
You may try to switch to its fork by Kirill, there is -reuse
switch.
Or, you may switch to ConEmu - another free terminal emulator (I'm the author). It may be configured as "single instance" in settings, or you may use /single
switch with ConEmu.exe. Also, you may create new tab from existing tab using -new_console switch. E.g. type in cmd prompt putty -new_console
and it will starts in new ConEmu's tab.