switching my workout

well i was using this workout for about 6 months and i think i hit the wall i mean i reached a plateau my workout was
mon:chest/bi
tue:abs
wed:back/tri
thu:abs
friday:shoulders/traps
sat:legs/calves
sunday:rest

as u can see i hit every muscle once a week well should i switch my workout to a workout wher i hit the big muscles (ches/back/legs) once every 7 days and small muscles once every 4 days? and if yes can some 1 post me a good workout but take in consideration sunday should be rest coz the gym dont open on sunday thanx