If you are looking for different extraction methods to increase the essential oil or oil components, follow the following threads. Both the essential oil yield and the percentages of components are under the influence of several factors. It is difficult to increase the yield of a phytochemical by changing the method of extraction if the plant contains low amounts of the phytochemical.

Essential oil and its constituents are biosynthesized from the products of photosynthesis through a series of steps involving several enzymes and possibly genes. To increase the concentration of a particular component it is essential to know the biosynthetic steps and plan for ways of enhancing the component through regulating these steps which is tedious and time consuming.

The other method is to screen a large number of available germplasm for genotypes having high content of the desired phytochemial. Chemotypes are common in aromatic plants and the existence of chemotypes with high content of D-limonene in your test plants is a possibility that needs to be explored.

A third method is to bred varieties high in D-limonene content. This again is time consuming.

Another easier way is to increase the biomass yield through agronomic manipulation, which in turn will increase the essential oil yield per unit area. From higher yield of essential oil more D-limonene can be extracted.

You can check the list of  plant species whose essential oils are rich in D-limonene from Dr. Duke's phytochemical and ethnobotanical databases and select plants of your choice.

D-limonene or essential oils rich in D-limonene are available in the market. You can purchase it and develop your drug.

Since you have not mentioned your objective clearly, I have provided many options.

https://www.researchgate.net/post/Can_a_solvent_effect_the_nature_of_plant_constituents_or_the_structure_of_a_natural_plant_product

https://www.researchgate.net/post/What_are_the_techniques_used_for_the_extraction_of_essential_oils_from_a_plant

https://www.researchgate.net/post/Is_anyone_working_on_new_techniques_of_distilling_aromatic_plants_to_produce_essential_oils

https://www.researchgate.net/post/Which_methods_can_be_used_to_identify_and_authenticate_essential_oil_constituents

Dear Dr. Ping,

Normally scientists followed seasonal variations to see the highest yield or percent of specific constituent in essential oils. Some times it helped to get highest percentage of specific constituents. Otherway, you need to develop a high yielding variety ( through genetic engening techniques-firstly identified a specific gene which helps to produce specific compound in plants) which produce maximum percent of your desire compound (In this case D-limonene). This is extensively hard and also time consuming. But you can try. Best of luck.

Dear Mohammad,

I agree that checking seasonal variations will be helpful. And different locations may also be important.

To develop a high yield is a good idea. It is possible but not my expertise. 

Dear  Ping Zhang

It all depends on whether you want to increase the detectability of this component, or above all its content in essential oil from a given material. The easiest way of course is to identify the gene, which is responsible for the accumulation of the plant and the production of a component, but what it is the easiest? it's not that easy, unless you have mastered genetics and ways to identify these genes, which even those skilled nieprzychodzi easily.

Growing conditions are a factor modifying the contents of each of the components in the oil, but also the method of harvesting, drying, storage. You can not always adopt the conditions from one experience to another. Because if they did this in all questions we'd know the answer already. You have to try to fit some solutions, it can be useful.

I recommend

Dear Dr Ping Zhang,

Harvesting time may influence the d-limonene content of citrus essential oils - for example, Citrus limon fruit has its highest limonene content when immature, see: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3353483/pdf/TSWJ2012-528593.pdf

Best Wishes, John Tye.