Low power

Hey all. I just broke my grizzly back out after about a month of sitting since my last ride. Let her warm up and ran her around my property. When I really hit the throttle she didn’t have near the power it’s supposed too. Couldn’t break 25mph. Sounds like it does when the belt gets wet and slips. I did get it wet last ride and she slipped on me. Do I need a new belt? Or is this a worse problem?