Upgrade from W5 to W7?

I see a $99 upgrade from W6 to W7, but I have W5.

Is there a discounted upgrade, or am I going to have to buy the whole thing again?

Please ask your distributor. We have no knowledge about commercial matters here.

Do you really need to upgrade?

There are definitely features that have been added since Wavelab 5 (DAW transport control, for one), that are worth the $99, but not $500 at this point.