if you're giving the wormer that also covers heart worm - you might not want to give it every 2 days.
The way wormers are usually used - is not *after* you see them but on a regular basis before you see them - so their numbers are kept low and problems are *prevented*. It may be that you do need a stronger or more frequent dose if there are lots of worms already present.
At this point - I'd be asking your vet for more advice. the excelpet website does not list the active ingredients for their wormers so I can't google the info.
It does help to vary what chemical you use for parasite treatments from time to time - eg something different each year maybe - as they can build up resistance. But with worms - it's mostly about keeping the numbers down. Then again - I've never seen a worm in my dog's poo and I do check - especially the pink ones. The closest we get is long bits of grass or dog fur.