improve,better,make better,ameliorate,reform,enhance,add to,customize,touch up,rehabilitate,refurbish,recondition,modernize,update,bring up to date,renovate,redecorate,revamp,restore,remodel,redo,brighten up,spruce up,bring up to code
do up,fix up
promote,give a higher rank to,place in a higher rank,give promotion to,give a higher position to,elevate,advance,move up,raise,lift,boost,improve the position/status of,aggrandize,exaltupgrade
raise (something) to a higher standard in particular improve (equipment or machinery) by adding or replacing components.
the cost of upgrading each workstation is around $300
an act of upgrading something.upgrade