Replace the sending unit, aka oil pressure switch. They are known to go bad. Should be like 30bux.
The beauty of the jeep is that it will run with zero pressure or almost no oil at all. Not a big worry, but the sending unit is the problem. Check out jeep forums.
https://www.google.com/#sclient=psy-ab&q=2001%20jeep%20cherokee%20high%20oil%20pressure&oq=&gs_l=&pbx=1&bav=on.2,or.r_cp.r_qf.&bvm=bv.49784469,d.dmg&fp=f91cd8e5275c41e&biw=1249&bih=558&pf=p&pdl=300