Was it the alcohol or the taste that was too strong IYKWIM?

I am guessing that since you made it last year you probably still have some.

I am also going to go with the alcohol being too strong - that is quite easy to fix. If you heat the brandy up in a saucepan the alcohol will burn off (so put more than you need in the saucepan as you will loose some from evaporation) and you can then let it cool and use it as you did last time.

If it was the brandy taste that was too strong maybe use half as much and add some cherry juice (which I saw in coles the other day - in a tin in the fruit juice section) to make up the volume difference. I wouldn't use water as I don't think that the flavour would be strong enough.