Sturridge fired 11 goals in just 16 games following his January move to L4 and Rush is a big fan of the No.15.
"Sturridge can get even better without a doubt," Rush told liverpoolfc.com.
"He's got some great skill and with a good pre-season I think you will see an even better Sturridge next season.
"He needs to get fully fit. He was absolutely incredible in some of the games. He has got a good football brain, Coutinho has as well - some of the passes he put through were absolutely superb.
"Sturridge has had a couple of little injuries but if he can get fully fit and get through the pre-season then I think there are exciting times ahead."