What do you mean you have the device entropy details?

When generating a private key, your computer collects entropy from various sources. Mouse movements, network activity, thermal noise etc. You can't just redo the process and expect to get the same entropy, because the entropy is dependent on beyond RAM and probably other hardware info. In fact, I think that preventing the recovery of an entropy is what the Cryptographically Secure Random Number Generator is trying to accomplish in the first place, for if it wasn't, other programs could work out your private keys.