Dont use that shikakai bar, first thing
There is shikakai and amla in the henna mix.
The navratna is nice on ur scalp, but it's not going to really help the henna give you a brighter red stain
You could add some oil(any oil) to the henna mix like 1tbsp to 10 oz of mixed henna paste
How dark is your hair, the stain from henna shows up on dark hair only in direct sunlight
Beet juice is interesting, hibiscus works well too, sorrell also.
good luck, rinse well
Don't use that bar