Though i would submit a separate post on how to attract butterflies specially in lahore, right now i would focus on only which plants i have found attractive for butterflies.
1- First, butterflies are cold blooded insects so they love sunshine. They tend to prefer area which receives maximum sunshine.
2- Choose flowers rich in nectar. Have you wondered why there is not a lot of butterflies seen on Roses? nectar!!!!! Nectar rich flowers are usually single petal flowers having large seeds visible in the center. See the example of Dahlia below:

Good for butterflies, Nectar Rich

Not butterfly friendly, no nectar
Daisy is another common example. Others good flowers include following:
- scabiosa (pincushion flower)
- Lantana(specially blue flowered)
- buddleia (butterfly bush, white color variety survives in plains while purple one in hills)
- Asclepias curassavica(tropical milkweed)
- lemon/orange/tangerine
- Kniphofia(red hot pocker)
- Allium
- Cosmos
- Single petal dahlia
- Hibiscus
And last but not least Senecio confusus vine. In this march i had more than 200 blooms on this vine and every single day it was surrounded by butterflies.
Butterfly on my senecio vine
3-Choose flowers with sweet fragrance. One example is Murraya (Marwa, marwi), i have seen hundreds of butterflies on one single murraya tree near my home.
Note that butterflies usually appear in lahore from February-October. Also, Butterflies cannot fly if their body temperature is less than 86 degrees.