tie the levers back to bars and leave for overnight will sort most things. Then just remove cap from lever (with lever level), top up with fluid.
If you have too much travel on the levers (common with saints), attach tube & syringe to calliper, open bleed nut, suck out any air, allow bubbles to rise into syringe then inject extra fluid into the system so it is pressurised. Close nipple, try lever, repeat as necessary.
ALWAYS add some negative pressure to the syringe before disconnecting the tube from bleed nipple though otherwise you’ll squirt oil everywhere as it’s basically under pressure!