Monarchy was finished after 1918, with a majority of Germans opposing it the chances for a revival were minimal all the time.  The "Kapp-Putsch" shows this quite well.  [XXXttp://en.wikipedia.org/wiki/Kapp_Putsch] 

 

What made the Weimar Republic fail was mainly the economy.  Even the Nazis did only play a major role in the last years of the first German Republic.  Additionally as already mentioned, there was only about a third of political parties aiming at the stabilisation of Democracy, while the left and right were busy at destabilising the system.  The right in favor of Monarchy, the Communists and parts of the Social Democracy for Communist Revolution or a "Räterepublik"  - Soviet Republic with "worker - peasant - soldier" commitees running the state.