"The above prompt argument " - does not make sense.
"fails to provide evidence to support the
assumption that reducing the price of Mercury newspaper – lower than Bugle will increase the number of readers. " - I think you meant conclusion.
"Mercury feels that lowering
that cost than Bugle " - what cost are you referring to?
"regain
their lost 10,000 readers" - its?
"The argument is confident that ..." - too colloquial.
"an increase in reader" - does not make any sense.
"It could be the case that businesses are not advertising in the Bugle instead are using other forms of media or digital
adverting." - not a proper sentence. Adverting??
"other reasons to decline in the number" - ungrammatical.
"The Bugle might be more of a social newspaper that Mercury thus appealing to the new generation." - not a sentence.
I have highlighted a few grammatical errors in your essay. You need to allocate 3-5 mins to weed out grammar/spelling/punctuation errors before submitting the essay.
Also, you can improve the way your essay is structured. here are a few sample essays -
https://gmat.crackverbal.com/gmat-awa/You can also add a few more points -
What if the bugle also reduces its price in response to Mercury's actions?
What if the population of the town has declined over the past 5 years?
What if the Bugle has better content?
What if reducing the price is unsustainable and leads to massive losses?
What if reducing the price affects Mercury's brand image?
What if the circulation of another newspaper that is priced higher than the Mercury has increased?
What if the gains in advertising revenue through increased circulation are less than the losses sustained due to loss of revenue through price reduction?
What if increased circulation would not attract advertisers as they find the readership of bugle to closely resemble their target audience?
What if there is a better strategy than reducing prices? for example - the paper can target new markets/cities; or maybe it can include more content for the same price.