Is there anything I can do to perk up my mower after the winter?

I forgot to add fuel stabilizer in the fall before storing my Craftsman push mower in my garden shed. I live in Iowa. Now my mower is sputtering and running pretty rough. Are there any fuel additives I can use to perk it up? I don't want to mess around with draining the gas and adding fresh gas. It ran just fine last fall.