Answer

Yes, you may buy juice while wearing your pooja clothes, but from a Jain Dharma perspective it is better to maintain the purity and purpose of those clothes.

Explanation

Pooja clothes are usually kept clean and reserved for worship, temple, and religious activities. If you go outside to buy juice:

• The clothes may become dusty or impure.
• You may come into contact with worldly activity immediately after pooja.
• The devotional feeling of pooja may reduce.

So, if possible, it is better to change into regular clothes before going out.

Spiritual Understanding

In Jain practice, external purity supports internal purity. Pooja clothes remind us of reverence, discipline, and spiritual focus. Keeping them specially for religious use helps preserve that bhav.

Takeaway

It is not a major fault simply to buy juice in pooja clothes, but ideally, change clothes first if you can. If you must go, remain careful, respectful, and mindful.