Cosmos sake on kepler help

CosmosCosmos
$11.54
0.39%
self.cosmosnetwork8m ago
Hello I'm new to staking atom on Kepler. I had atom staked on the sg-1 delegator. I had a decent amount of rewards built up and then I added more atom to stake on sg-1 and the previous rewards disappeared and started from scratch. Is there a way to get those rewards back or are they lost? If I want to keep adding atom to stake I have to unstake all of them ?