I do not agree with you dear,
I had a buyer who was not able to buy my premium package because of the pricing was higher.
and he bought my basic package.
after a few days I have lower my gig pricing for few reasons.
and when I offered him the new pricing, he placed an order on my premium gig instantly.
so I think it totally depends on how satisfied the buyer was when you did the last work with him/her.
If you both have a good connection, there is no issue to Approach for new work.
( its totally my personal opinion) .
I am not sure about the Fiverr TOS about this part.