Squonk's Mandarin idea sounds like it might help.
I can't remember where I picked this up, but I read somewhere about using 2% fa Orange + 1 cap Tangerine + 0.5 fa Bergamot + 2.5 fa Lemon, to approximate fruit circles ("froot loops") flavor.
I've never owned either tfa fruit circles OR cap sweet tangerine, so I use either an extra percentage of fa Orange or 0.75% fa Mandarin in this mix in its place. Either way, it tastes a lot like the real thing. (The "real thing", meaning the fro0t loops cereal flavor). This won't give you whatever grainy/corny or cereal-like component tfa fruit circles may have, but you can use something else for that if you want it, say fa cookie and/or tiny bit of acetyl pyrazine.
That probably seems like a lot of trouble, considering you already have the fruit circles flavor..

In case nobody's mentioned, lemon/lime flavors tend to fade out pretty significantly over a few weeks, so you could also try just waiting.