I just took the name from Nemtsov's proposed name for a monarchical Russia.I don't see the Russians changing the country name to the Czardom of Russia. They would probably adopt an arrangement similar to Japan, where they would retain the name "Russia" but would also give their monarch the proper title. But I dunno, Russians are a pretty unpredictable. They could also like to adopt such a chocking title to mock western countries and their dull federal republics.
Also, considering that the Romanov family ruler over a lot of nations, what is the support for a monarchical restoration in Ukraine? They are, as far as I can see, the only ex-Russian Empire country who COULD (in my limited understanding) restore the Romanov to the throne and assume a personal union with Russia, similar to Britain and Canada.