Here is a way to semi-permanently raise a stat in TES: Arena (tested only in 1.06):

1. Create a spell to fortify a stat, or acquire an item to cast such a spell. (By far, the Potion of Strength is the easiest such item to get, though you'll need at least 2.) Note that I suggest not changing the rate of return; you don't want it too fast for this purpose, and slowing it down doesn't seem to work.
2. Use the spell to raise the stat.
3. Wait for the spell to wear off. At this point, your stat will gradually return to normal.
4. Before it returns to normal, cast the spell again. This will set the normal value (but not the base value) to the value it was when you recast the spell.
5. Once the second fortify wears off, what was left of the first one is now semi-permanent, and you can repeat for higher stats.

There are, however, a couple catches to this:
1. If you level up, you will lose all the stats you gained with this trick. Same if you pick up the Oghma Infinium.
2. If you lose stats gained from this exploit to disease or curse, you will not recover them when you rest (except to your base value, if your stat drops lower than that), and will need to repeat the exploit.
3. I do not know whether Fortify Endurance affects Health gains at level up.