HVAC Carrier 38chc

AC central unit that is 9 years old, that had to be recharged and seem to be hold it. The tech that had done the work said there must be a leak and the unit should be replaced. Should I have it repaired or replaced? If replaced what brand should I be looking at? I really don't want to replaced the furnace because it's only 9yrs old and have not had a problem with it.