Suggestion.
The game needs accounts that can be attacked and it is no loss. In all previous exploits to O Game or games of similar character. There has been the same problem. The player base.
Many accounts are made and forgotten. This would be an average over 60% for most games of past brought to recollection. Players of all levels need accounts to attack. The higher levels gameplay or pay to advance diminish the start of many casual players and their ability to gain any growth is hindered by constant attacks.

This loses much of the player base needed for the next levels of the game. Planets that will grow automatically also fail to deliver much of what is needed.

With agreement.

This can be done easily by making two Clans in the game. Used to create gameplay advancement for players. The advantages of these accounts is resources on planets for players to take advantage of. These planets do not attack players.

The first Clan would be fodder. Named as such. These accounts would be available for players to attack. They would also provide a better resource than attacking a playing player. They can supply resources for multiple accounts to grow from.

The second Clan would be named Planet Builder. This account and others in the clan would grow to provide more planets at newer destinations of greater production power.

Players that grow. Can request an upgrade to a planet that has died. (Too low for anyone to plunder.) This fee can be paid in PIZZA the game token already used.

More players play longer learn more and play better the next server.

The game might also offer daily rewards for playing. This would be a capped limit reward. For logging in completing the task of using up x amount of resources you gain 10 PIZZA credits 50% can be used in the server and 50% credited to the next server.

I see you are slacking on servers. :P
Have you considered options for other servers?
Have you considered how the game can be played that is not the way it has always been played.
Have you considered other ways of gameplay for both long and short games.

Have several variations of the game ready to go at any time. Some servers can run for months to a year. Other sever might be as low as two or three months.