Value Improvement limits Q

[Xrati]

Don't be so quick to scrap, as depending how 'hard' you are mining your planet, the value may still drop. I built a sphereworld and built one value improvement on it. A lot of turns later after I built mining facilites the value started dropping again. I built another value improvement facility and the value started to go up again!

[Alneyan]

Were you playing a mod? In the stock game, facilities do not make values go down, and you cannot remote-mine a colonised planet. The only thing that can make values go down is an event (in stock), or possibly intelligence.