You can do this with your file. For instance, the default is this:
xp.current..'/'..xp.tnl..'XP '..lp.current..'/'..lp.tnm..'LP ['..lp.number_of_merits..'/'..lp.maximum_merits..'] XP/hr:'..string.format('%.1f',math.floor(xp.rate/100)/10)..'k '..cp.current..'/'..cp.tnjp..'CP ['..cp.number_of_job_points..'] CP/hr:'..string.format('%.1f',math.floor(cp.rate/100)/10)..'k'
But you can change your default to be this:
xp.current..'/'..xp.tnl..'XP ('..(xp.tnl-xp.current)..') '..lp.current..'/'..lp.tnm..'LP ('..(lp.tnm-lp.current)..') '['..lp.number_of_merits..'/'..lp.maximum_merits..'] XP/hr:'..string.format('%.1f',math.floor(xp.rate/100)/10)..'k '..cp.current..'/'..cp.tnjp..'CP ['..cp.number_of_job_points..'] CP/hr:'..string.format('%.1f',math.floor(cp.rate/100)/10)..'k'
Notice how I added the xp.tnl-xp.current and lp.tnm-lp.current? Those should tell you how much you have remaining until the next level or merit.