looking at it further, I find you have a strong simple iconic form - which is definitely where you want to start (you don't want to start with something weak & then tart it up)
& you already have ~9months of customers who recognize this as icon of your product, so I'd suggest that you don't change overall icon….
so, use that as starting place &
explore adding some surface texture & or sheen, such as in Apple Messages - although that has been overdone, so then could look at coming up with a unique surface look, or variation - PS Express has a very simple overall gradient, which should work well with your colors
also, could explore changing the colors - slightly - yes, I know they are google colors & this might make it worse, but perhaps, de-saturate them slightly, would give it a more sophisticated feel - depends, being same as google is strong statement & worth perhaps holding onto
but change them & would make it more "unique to you" while still connecting to google brand
(and any change is always a change, part of the magic of changing, is just that, a change… think new colors of Nanos, or magazine covers… yes, there are trends, but also, it's just new)
could explore total change of color with same shape (always connecting back to existing brand) such as into golds of silver or something
& finally - hold off on putting into product until some totally larger overall of product release/features