Lumpty Bumpty Lawn ! !

I have got a fairly large lawn which has got very lumpy and bumpy due to my regular arguments with moles then dogs digging for moles etc. etc.  In fact in places it is very hard to cut it properly.  I am over middle aged with disabled other half so want to even it out with as little work as poss.  i cannot afford to get man in to do it.   Would it be okay if I just got a load of new topsoil, spread evenly over rough area, roll and fence off from dogs then just reseed ?  Will it be ok to do this without  digging up the present lawn grass ?   Help please