My battery isn't lasting long

I own a huawei watch fit,it is about a year or so old and I have started noticing that my battery isn't lasting long,when I first bought the watch 100% would last about a week or so but now(after a few software updates and a year of usage) the 100% only lasts 3 to 4 days,I think the battery is to blame but I want to know if I can do something else to fix it as my local huawei store don't replace watch batteries for my model