Should I respec workshop?

I'm a new player at the point where my runs end because of vampires. After searching on here I learned that the general tips is to keep your knock back at 0 in order to use thorns on them. I invested a good amount of coins into knock back when I was starting. Should I respec my workshop to get over this hurdle? The highest Tier 2 I have completed is 844 but that seems like luck based on the vampire spawn chance. I did get the target selection researched and put it on basic. That does not seem to be helping. My last few runs ended in the high 700s.