It's really only the tips of the serrations that blunt in general use. As this knife is a fairly cheap user, I wouldn't worry too much about getting right into the curves as I doubt they're blunt.
As suggested, some wet and dry paper on a flat surface. It'll pick up the straight edge and sharpen the tips of the serrations.
As for replacements, you'll need to tell us more about use, as in locking or not etc. There are many knives that may suit, the Chinese (Sanrenmu, Ganzo, Navy) offerings being very good value for money.
If I'm honest, that knife looks uncomfortable in use, and is a locker so unsuitable for everyday pocket carry. If you can carry a locking knife as a daily user, then I may have something far more capable for you. Been clearing the cupboard, turned up a few.