This is what you can do if you want to extend the joints life.Take the large band clamp,the one at the wheel end,off.It will have to be cut off.Push the boot back toward the trans. enough to be able to see the inside of the joint.
If the boot is stuck,you may have to cut off the small band clamp too.
Clean out the grease that is in the joint with brake cleaner.Spray the cleaner in the joint and boot.Get all of the grease out that you can.Check the boot for grease too and remove any in it.
Clean out the brake cleaner that may be left,make sure the joint and boot are as dry as possible before adding the new grease.
Take a grease needle and put grease up into the joint around the ball bearings,do this at each bearing.Fill them up as much as possible.
Take you fingers,you may want to wear latex gloves,and push the grease into the joint,adding more with your fingers if needed.Add extra grease to the boot at the same end as the joint.
Put the boot back on the joint and use a large worm clamp to hold it in place.Make sure that there is enough clearance for the clamp to turn with the axle and not hit anything,it should be ok.
If you removed the small clamp/band,replace it with a new worm clamp too.
This trick should get you several more hundred,if not,thousands of miles from the joints.
This may sound like a big job but the hardest part is getting the original clamp/band off of the boot.