When is it time to update to a iphone 5s onwards from a iphone4?

Hi

What clues do your phones provide to tell you it's time to upgrade to a newer phone

Have a iphone 4 and it's doing following

battery doesn't last now

caneras not best

Closes out of apps for no reason internet crashes

sometimes it's very slow on internet what makes iphone5s on better with that

There's no more updates and all apps now need newer operating system than iphone4 can take

Won't name rest of problems as list is too big otherwise

What can you do to get your old iphone4 to hang on a bit longer and have trouble free internet and be able to have some new apps if you can't afford a iphone6 yet due to other expenses

I've been upgrading every other year. I don't wait for problems to start - and find that about every two years the technology has changed enough where it makes sense because enough new features are available.

How about a refurbished 6s from Apple?

Is a normal iphone 5 a big upgrade from the 4