Instead of generating random cards generate random hands from a table
((r1)Straight flush,(c1)Straight flush), ((r2)Straight flush,(c2)Straight flush),(Four of a kind,Full house) ..
Check if it is possible to have such a combination.
Another possibility, while the score suck , flip the board and redraw or randomly rearrange.
If score suck, rearrange to increase score.
While score low, redraw half of the bad cards