There is a tear stain mix that you can get at pet stores.. Just ask for a Tear stain mixture and they should point you in the right direction. Other then that.. you might need to start soaping in the area and rinsing it weekly!
well wipe with baby wipes in morning and afternoon to cut dwn on build up i use vapet tear stain remover which is great it really works it takes a week though to get rid of stains completly though