Are there still lime bloods on alternia? I know not many but maybe just a few who managed to hide?

Arguably, by the time the Beta Trolls are born, Limes are extinct. ‘A few who managed to hide’ is highly unlikely, given Trolls are born on Alternia from a single source, the Mother Grub, so every single Lime that was born, if any at all, after the Extermination, should be accounted for and taken care of.

That being said, if you’re talking about Hiveswap rather than Homestuck, there’s reasonable evidence that we’re going to see Limes, implying for them to have survived in extremely reduced numbers, or for whatever event led to their Extermination by hand of the Highbloods to come after Hiveswap, or dare I say, happen as a result of the events in Hiveswap.