No, you could not.
As already explained by several people, to keep your extension of permit to stay valid, you must get a re-entry permit before you go, otherwise your permit to stay automatically ends when you leave.
They actually put a stamp in your passport now, when you get an extension, that tells you this. It says:
Otherwise, on returning without either a re-entry permit (or a new, valid, longer term visa issued while you were away) you would only have been stamped in for 30 days visa exempt (assuming you were eligible).