Strangely enough, I think I can relate. Sushi used to be a fairly special meal (due to availability and expense), however after moving to Chicago and finding an abundance of relatively affordable seafood retailers, it became a "regular" weekly meal.
My palate in the beginning was fairly limited. Maki and maybe unagi.
Then I found that I'd over-unagi'd myself.
I moved on to salmon and for a period sake was a favorite - I could eat plates and plates of raw salmon, then... as others have mentioned in the past, I over-salmon-ed myself (raw & cooked).
After "wearing out" unagi & salmon, I moved on to loving maguro, then slowly all the other exotic cuts of tuna, as well as other species including bluefin and bigeye (vs plain old yellowfin).
I added fish roe to my palate, all the various shellfish, large raw spot prawns, any other type of fish besides tuna, eel or salmon...
Then... we realized we'd over-sushi'd ourselves... of course it was only possible b/c we'd always made sushi at home (thereby at a fraction of the cost). This also made it possible to have sushi 2-3 times in a week months on end.
Just like anything, variety is the spice of life and we'd simply overdone it.
For yourself, perhaps adding some varieties in your fish/shellfish may re-spark your interest in sushi.
For us, it'll just have to be abstinence...