My heart output is 31%can it be improved without a stent?

Possibly. It all depends on the cause of your heart failure. If it is coronary artery disease, you may need to have stents placed in order to help your heart's blood supply and also your ejection fraction (heart output). If your heart failure has another cause (uncontrolled blood pressure, cardiomyopathy, valvular disease), those need to be treated adequately to help restore its function.
Not likely. If you have a depressed ejection fraction then you need to be under the care of a physician. Speaking in generalities, you will need to be on medication to reduce your blood pressure to cause what is caused after load reduction. If you have heart disease, meaning coronary artery disease, then this will need to be addressed aggressively as well.