As my stylist always tells me, you can't repair a split end, you have to trim them.

But use a deep treatment like hair serum or hair mask (yes, they exist!) to give the ends some strength. Sephora has some great products by Frederic Fekkai, like the protein treatment mask and the Protein Rx reparative shampoo.

Or do what I did i highschool and snip them off in math class :)