Take the cranks off and grease the thread and put them back on using a 8mm Allen key. Sound like the thread in the lever body itself has stripped. Not sure on a fix on that, whether it can be Helicoiled or not. Best bet would be try to pick up a second hand body off here. Theres a number of things you can do to make the lever futher away. First would be to set your rear brake up so the pads are closer to the rim. You can adjust the TPA on the lever which pushes the pistons closer to the rim. You can also get new pads which have more material. Only if your current ones are worn down though!
Hope this helps.