1997 Honda Civic Changing the seals for the timing belt

Engine Mechanical problem
1997 Honda Civic 4 cyl Front Wheel Drive Automatic 170k miles

If I have had the timing belt changed, how often could the seals that pertain to the timing cover crank seal be changed?
It has been 70 k miles since the timing belt was changed last and when does the belt itself have to be changed again?

Thank you in advance,
carrie