If this is like other masternode coins, you will have to put your leftover coins in another wallet to stake them. The reason for this is a masternode requires on input to be a specific amount. When you stake, the input is split, so your masternode will no longer work. (Staking has to be shut off in the wallet running the masternode) There are several ways to run more than one wallet instance on one machine. Or you can have two wallets running on different machines.