Older saws with riser blocks set up for resaw often had 3/4hp or smaller motors on them. You should be fine if you slow your feed rate down as your cuts get taller and in harder wood. It's not a "commercial" setup, but you probably don't need to feed a ton of lineal feet of resawing through the machine each day to make the thing earn its keep. For a hobbyist, 3/4 hp should be fine. Force feeding thick cuts through this machine will lead to other problems as well, not just undo strain on the motor. Take it easy - let the machine do it's work and you should be fine.
I've got an old Crescent 20" saw with a 1" 3tpi blade and a 1hp motor. It will resaw up to just a hair under 12". For most tasks it's fine, but the taller cuts in harder wood do require me to slow down the feed rate a bit - pay more attention to what i'm doing. The cut quality doesn't suffer, i'm just standing at the saw a few seconds longer for each cut - big deal.
Before i got the 20" saw, i was occassionally resawing up to 8" tall with a 1/2" 4tpi blade and a 1/2 hp motor on a smaller, off brand saw. That saw was never meant to resaw, but if i didn't force things, it worked fine. I didn't upgrade my saw because of any dissatisfaction, the Crescent fell in my lap - free for the taking.
This is my hobby, not my job. I enjoy my time in the shop. I try to speed up or avoid tasks i don't like (such as sanding), but sawing isn't one of them.
If it were me (and i know it's not) i'd go with the riser kit if i thought i'd use it. Then, if you really get frustrated with the motor, you can always upgrade that as well at a later date.
I guess the other option would be to spend no effort upgrading your saw and look into bigger, more powerful machines, but that seems like a stretch for someone who just needs a new blade.
If you're wearing out blades, that's good - you're getting your money's worth from your saw.
have fun with it.
Paul Hubbman