Hello and welcome to the forum.
I'm sorry I can't advise on the Lantus v Levemir issue: I'm on Lantus and NovoRapid. I don't feel great on Lantus, but can't be sure it's the Lantus, I have been on it a long time, and it has never occurred to me that I should try another type of insulin.
Anyway, there will be a range of advice from people on here who know about both. I hope you feel better soon. Do you think your lack of energy could be dosage- or diet-related?