hi there
i had the same problem as you, except my dt was too high
the only way to higher or lower the bike is to make some new suspension links.
If you look under your swingarm you will find these.
The ones im holding are the original yamaha ones, ones on my bike are the custom ones.
The longer they are the lower the rear end.
So, if you want to make it higher all you would have to do is make the suspension links shorter.
Oh and make sure you loosen your chain alot before you put them on
hope this helps.