Do I have to put suet in my canned mincemeat?
Historically, minced meat really was a meat dish, prepared with the fat and meat of game, such as venison.  Today's pie fillings sometimes honor this history by including suet as the fat of choice.

It is critical that you follow recipes that are designed for canning precisely, since the are balanced to ensure that all of the factors come together to provide a safe product.

You may be able to find another canned minced meat recipe from a reputable source which does not include suet, although I did not have much luck.

If you do not insist on canning, you should be able to freeze mincemeat for at least six months, in which case you can substitute more freely.  The most common substitute is butter.