It's frustrating that there is so little information available about Ropsha, isn't it, nigbil?
Ropsha, which was designed by Rastrelli, was Imperial property, but appears to have been used primarily by Grand Duke Valdimir and his family. I think it was used for typical country pursuits. As noted, Catherine II had Peter III imprisoned there until he was murdered.
The palace and the paper factory on the grounds (which I presume was built after the Revolution, but I may be wrong) was rebuilt after WWII. Unfortunately, the palace again was gutted by fire some years back and is now in the condition we see it today.
I am unaware of any restoration project going on. I think the scaffolding is there merely to keep the building from falling. With the horrendous lack of resources available to palaces of much more historical significance in Russia, I find it unlikely that Ropsha will be rebuilt and restored.