Ridhima, who already has one win against her name this season, carded one-under 71 to get to seven-under 137, the lowest two-round aggregate this season.
She now leads by four shots at the end of Round 2 over amateur Anika Varma, who shot a second straight 71 to reach three-under 141 and now sits two shots clear of the third placed Gaurika Bishnoi (73) at the Jaypee Greens.
Asmitha, who had the first day's second best score of 68, slipped to 82 on the second day as she lapsed into a series of errors including a triple bogey and a double bogey.
Amateur Nayanika Sanga (76) and Afshan Fatima (78) complete the Top-10.
Experienced Gursimar Badwal (81-73) and Neha Tripathi (77-77) were trailing way behind in tied-12th place, and Smriti Mehra (83-76) was lying at 20th.
Ridhima won twice in 2018, but one of the wins was as an amateur. She added a third Hero WPGT win at the fourth leg this season.
In the first round, Ridhima recorded the season's best round on a par 72 course. At six-under 66, she bettered Neha's effort of five-under 66 in the second round of the first leg on the par-71 Poona Club Golf Course.
In the second round, Ridhima, who played for India at the 2018 Asian Games in Jakarta, birdied the first and sixth but gave away those gains with bogeys on seventh and ninth to turn in even par. A birdie on par-5 13th and Par-4 17th with a bogey on Par-4 14th meant she finished at 71.
Amateur Anika Varma seemed in line for an even better round than her first day's 71 as she was five-under and bogey free when she arrived at the 15th tee. She then dropped three shots in four holes at the 15th, 17th and 18th to finish at two-under 70, and was four behind leader Ridhima.
Gaurika, too, had a disappointing bogey-bogey finish after being one-under through 16 holes. She birdied first, sixth and 11th but dropped a double bogey on second before the bogeys on the last two holes.
First day's star amateur, Asmitha, struggled in the second round. She triple bogeyed the Par-5 third, bogeyed fourth, double bogeyed sixth and again bogeyed ninth and had just one birdie on Par-3 eighth as she turned in six-over 42.
On the back nine she bogeyed four times and had no birdies for a 40 and a day's card of 82, as she slipped from second to tied-seventh.
The fifth group comprises Gursimar Badwal, amateur Natalii Gupta and Afshan Fatima, followed by amateurs Nayanika Sanga and Asmitha Sathish with Ananya Datar in the sixth.
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