Cheat: Full Arsenal
Super Castlevania IV is about as challenging as any game in the series. To make it all the way to Dracula means you most likely have the skill to defeat him with additional help. In case you do want some help, you can get a full arsenal of max health, 99 hearts, a cross, a III stone, and a fully upgraded whip.
To do this, go to the screen with the stairs leading to Dracula. Don't climb it; instead, jump to the left. Notice you're on an invisible platform. Go all the way left of the screen to find the upgrades.