Conversion of ambiguous left recursive grammar to LL(1)
I don't want to do your homework, but the two insights that appear to solve it for me are:


What the first rules

$S \rightarrow SoS$

$S \rightarrow SlSr$


say is that whatever else $S$ can be rewritten to (which, in this case, is just $i$) can be followed by any number of occurrences of $oS$ and $lSr$ arbitrarily often.


If we introduce a nonterminal for that (the part that follows the $i$), left-factorized rules for it follow immediately.