My Crazy Cell Phone

I don't believe this! I'm now charging my cell phone battery for the 2nd day in a row, and I still only have 2 battery strength bars- making my battery juice only at 1/3 of it's usual power. Normally, I don't charge the battery for two days. However, the battery has lately begun to need a longer period of charging than it used to. That's strange, considering that I only used my cell phone for only 1 very important call within the last week or so, as well as periodically checking in with my parents- to let them know if I needed anything or to let them know the latest on the Mary Bryant Home endavour.
I've had my cell phone for 2 1/2-3 years, now, and I'm beginning to think that a replacement battery might be in order. Thus, that might be challenging. Unlike my dad's phone, I can't charge the battery by itself- while having a replacement battery in the phone. To me, this sounds like I'm going to need a new phone.