My air conditioner isn’t cooling well

I’ve had this window unit for maybe 3-4 years and I believe it’s 10,000 btus. I have it set to 65, it’s reading 70° inside (I have the Frigidaire app) and it’s 71° outside right now. At the beginning of the summer, it would read 64° or 65° inside and now I’m lucky if it gets to 68° or 69°. It does fill up with water quite a bit at the bottom of the unit. Do I just need to buy a new one? Not sure if it’s just toast 😩