Yes, you most certainly can.

Mutual fund houses allow you to invest in mutual fund schemes whichever way you like.

So, if you have an ongoing SIP with a mutual fund house in say scheme A, you can definitely add more amount as lump sum in the same scheme.

When you invest in a fund (either via lump sum or SIP), you get a folio number, which is similar to your bank account and bank account number. Just like you can add money to your bank account either in five regular transactions or in one transaction, you can add investment amount to your existing mutual fund.

This is actually how experienced investors make the most of their investments.

Let’s say a mutual fund scheme is outperforming its peers and giving Mr. A stellar returns. Suppose Mr. A just sold a house and has good amount of money in his hands, ready to be mobilised. Impressed by the performance of the fund, Mr. A can invest lump sum amount in the same mutual fund scheme. This not only helps average the buying cost of the scheme, but also ensures your money keep growing.