Formal:
* आपका प्रेम कभी नहीं खोया (aapka prem kabhi nahin khoya): This literally translates to "Your love never lost" and is a formal way to say it.
* आपका प्रेम हमेशा रहेगा (aapka prem hamesha rahega): This translates to "Your love will always remain" and is a more poetic way to say it.
Informal:
* तुम्हारा प्यार कभी नहीं गया (tumhara pyaar kabhi nahin gaya): This literally translates to "Your love never went" and is a more informal way to say it.
* तुम्हारा प्यार हमेशा मेरे साथ रहेगा (tumhara pyaar hamesha mere saath rahega): This translates to "Your love will always remain with me" and is a more personal way to say it.
You can also use more poetic language to express the sentiment. For example, you could say:
* आपका प्रेम मेरे दिल में हमेशा जीवित रहेगा (aapka prem mere dil mein hamesha jeevit rahega): This translates to "Your love will always live in my heart."
The best way to say "your love never lost" in Hindi is to choose a phrase that feels natural and appropriate for the situation.