I'm going to go with G-3's idea ....
... it could be your hook size is too small, and you really aren't getting a good/deep hook penetration. I use #4 bronze Aberdeen lite wire hooks for Redear/Gill fishing (usually with pinch of nightcrawler as bait), and I don't lose many fish.
New line is always a good idea, especially if you fish alot ... fish in the sunshine alot ... fish cover alot (wood/rocks/etc) ... or store your rods in the trunk, bed, or backseat of your vehicle. Heat and sunlight will damage your line, over time.
I'm using Mr Crappie Super Hi-vis 4lb test line (old version, not the newer "chinese" made version) ... and I'm handling Crappie over 2lbs, Bass, Cats, Drum, Hybrids, etc. w/o fear of breakage. I've used the Improved Clinch knot about all of my life, on mono from 4lb test to 20lb test, and never had a problem with the knot. Improper cinching down of the knot, dry cinching of the knot, nicked/freyed line (from contact with cover), or kinked up line (from picked out birdsnests & professional overwinds) ... now those will cause problems :p
I'd change my line, first ... then, if I still lost fish (as before), I'd change hooks ;)
... cp :cool: