You can trickle charge the battery and get a bit more service.
Being a four year old battery though, I would consider eventual replacement. If there is any problem with the battery (dead cell, etc.), your alternator will have to work harder...
2009 ML350 (84K) - Family vehicle
2001 CLK430 Cabriolet (71K) - Wife's car
2005 BMW 645CI (124K) - My daily driver
2012 Mustang V6 (60K) - Daughter's car