bearing seals

i noticed grease had been sprayed on the inside of one of my front wheels. i took the hub off to find the grease in there had lost its viscosity. it was like water. the bearings are fine and all the seals look good, not perished or split. my question is do i need to replace these seals including the one that goes on the swivel housing as a little bit had leaked past that. or do i just put back together with fresh grease as these seals only failed to do their job because they are designed to hold back thicker stuff
cheers guys

Seems silly not to replace them considering the price of them and you have it apart anyway

yeah its just i haven't removed the swivel housing yet but i suppose its only another 10 mins work to get it off